Without any hesitation, Beth retrieved the next item from the shelf and held it up for me to see. It looked like another dildo, but it was made of a hard, white plastic, and it had a shiny metal tip that covered the top inch or two. I guessed it was overall about 8 to 10 inches long and about 1 inch in diameter. The most unique feature was that there were wires coming out of the bottom of it.

“This is called an RPE device, Jim,” Beth explained to me. “RPE stands for Rectal Probe Electrostimulation, which means it emits a harmless electric pulse. They use a similar kind of device on farm animals to obtain a forced ejaculation.”

Just great, I thought to myself, now she’s going to shove that thing up my ass and electrocute me until I cum.

“As you might have already guessed,” Beth continued, “this is going up your rectum and then we’ll run several tests using different electro-pulse patterns.” As she was talking, she began to lubricate the entire length of the device. I looked over at Ashley to see that she had a wide grin on her face as Beth described the device and what she was about to do to me.

“That doesn’t sound good at all. I don’t suppose I could talk you girls into just skipping this part,” I pleaded.

“No, Jim, you’ve gone this far, you need to finish all of the remaining tests,” said Ashley.

Once Beth finished making the device nice and slippery, she retrieved a second tube of material and applied the substance just to the metal tip. It looked similar to the lubricant, but it had a slightly thicker consistency.

“What’s that stuff?” I asked.

“This helps the metal electrode make good contact with you,” answered Beth as she smiled at me.

Beth approached me again and began to insert the device into my awaiting rectum. It slid in rather easily compared to the dildo. I guess it really helped that Beth loosened me up with the previous test. Once it was inserted all the way, Ashley plugged the wires into another small box that she had placed next to the laptop.

“I think we’re all set,” Ashley declared.

“Alright, we’ll start you on a very low level and a slow pulse,” said Beth as she motioned to Ashley to turn on the device. “You should feel a small pulse that repeats every few seconds.”

“Yeah, I feel it.” I saw that Ashley had begun the 30 second timer. She was right, the pulses were very faint, almost unnoticeable. Each pulse lasted less than a second, and repeated about once every three seconds. She said she would run several tests using this device, so I assumed this first one was just to make sure I didn’t experience any problems with it. I didn’t find this test arousing at all. In fact, it was actually pretty boring compared to what I’d already been through.

“That’s time,” announced Ashley. The pulses immediately stopped.

“OK, Jim,” said Beth, “we’re going to do that again, but this time the pulses will increase. And this test will run for 60 seconds instead of 30.”

As soon as Beth finished speaking, Ashley fiddled with some of the settings on the metal box and then flipped the switch that turned it on. I immediately felt the first very faint pulse. Then about two seconds later, the next pulse. But the second pulse was stronger and also lasted longer. And the third was even stronger and longer. Each pulse followed this pattern of getting progressively stronger and slightly longer in duration. This went on for about 5 pulses, then it started over at the lowest setting and started to build up again. After a couple of cycles, I really started to feel each pulse, especially the stronger ones. I felt myself getting harder, if that was even possible, and also beginning to feel as if I had to ejaculate. If was a very similar feeling to the prostate exam and massage that I had earlier. I looked at the count down on the laptop and saw that I still had 25 seconds to go. I then looked at Beth and Ashley and saw that both of them were smiling and intently watching the show that was taking place between my legs.

“Time,” announced Ashley as the pulses stopped.

“Alright, Jim, you’re doing fine,” said Beth. “Do you need a minute to rest before the next test?”

“No, I’m OK, let’s just get through this.”

“Alright, the next test is similar to the last one, but the pulses will go faster and build up a little stronger. And this time we’re going for 90 seconds. Here we go.” Beth once again motioned to Ashley to begin the test.

In a few seconds, I felt the first pulse again. It was very weak as before. But then the next pulse came almost immediately after the first one, with little or no break between them. And as in the last test, it was stronger than the first. The pattern continued as it did before, with each pulse getting stronger than the one before it, and lasting just a bit longer. After the 5th pulse, I was ready for the pattern to start again. But it didn’t. The 6th pulse was stronger, and so was the one after that. I lost count, but the pattern seemed to go up to about 12 pulses before it finally started over at the lowest setting again. And since each one was stronger than the one before it, the final few pulses were very strong, much stronger than I had felt before.

I looked at the count down on the laptop – still 65 seconds to go. I didn’t know if I would be able to last the entire 90 seconds. My palms were beginning to sweat, and I could feel sweat starting to build up on my chest and under my arms. My breathing was shallow, and each time one of the strongest pulses fired, I made a loud sound as if I was gasping for air. The strongest pulses even caused my entire body to tense up and involuntarily jerk. And each time the pattern repeated and built up in intensity, I felt the urge to ejaculate also increase. My cock felt like it was rock hard, and I was aching to get off right now. If my hands were free, I’d be stroking myself until I came, which probably wouldn’t take very long.

The count down now said 20 seconds to go, I was almost done. I really wanted to ejaculate, but I wasn’t quite there – at least not without some manual stimulation. And I was also trying to hold back as the girls instructed. I didn’t want to take the risk that we’d have to do the test over again. I think the cock strap must have been helping me to last longer, otherwise I probably would have shot my load by now. Just a few seconds more, 5, 4, 3, 2…

“Time,” Ashley announced.

To my relief, the pulses immediately stopped. I laid there trying to catch my breath and to allow my body to recover. Beth and Ashley were both huddled together reviewing the study instructions to see what was next.

“Are you OK, Jim?” Beth asked.

“Sure, I’m alright.”

“Well, the good news is that we only have one more test.” I watched as Beth began to remove the three sensors that were attached to my penis.

“My, you really got hard, on that last test, didn’t you?” Beth said as she continued to carefully disconnect and remove the sensors.

“What about this thing up my ass? Are you going to take that out now?” I thought it was a really good question.

“No, Jim, not yet,” replied Beth. “We still need that for this last test. And we’ll leave the cock strap in place too, I’m just removing the sensors since we don’t need them.”

I wondered what kind of test they would do that didn’t require the sensors. I thought the sensors were important since that’s how they measured my level of arousal.

“For this last test,” Beth continued, “we’re no longer measuring your size. It’s a timing test. We’ll use the RPE device as we did before, and we’ll time how long it takes you to ejaculate. I’m going to put this on you to make sure you don’t make too much of a mess.” Beth held up an unopened condom package and began to open it.

“But, you want me to actually cum this time?” I asked.

“That’s right. We’ll let the device run until you do.” Beth began to unroll the condom onto my erect penis as she was speaking. “If you don’t ejaculate during the first two minutes, the pulse intensity will increase. And then after two more minutes, it will go up again, and so on. The test will run for a maximum of 10 minutes!”

“Well, don’t get your hopes up Beth,” I said, “the way I feel right now I’ll probably last only about 30 seconds.”

“I wouldn’t be too sure,” she replied. “The strap you’re wearing will probably slow you down more than you think. And I think for most guys it’s more difficult to achieve an orgasm without some manual stimulation. But I’m pretty sure you won’t last 10 minutes. Are you ready to begin?”

I silently nodded my reply. In just a few seconds, I felt the pulses begin, very weak at first but then building up to a very strong level. It seemed that they were running the same pattern of about 12 pulses that they used for the previous test. I looked at the timer on the laptop and saw that this time it was counting up – 15, 16, 17. I wondered just how long it would take me to cum. And what was the goal of this test, to see how quickly I’d cum, or to see how long I could last? I didn’t know which results were good and which were bad.

Just as before, the constant barrage of pulses began to make me feel like I could cum at any minute. But then the pulses would start their pattern over again at the lowest setting, and I would temporarily lose the urge, only to have it build up again a few seconds later. It was as if the pattern was deliberately designed to keep me just on the edge. So far, the pulses weren’t enough to push me over the edge, but just kept me tantalizingly close to it. I looked at the timer again and saw that I was almost at the two minute mark.

“Two minutes,” I heard Ashley say.

The pulses now got stronger, all of them, from the lowest to the highest. It was as if the entire range of 12 pulses had now been shifted up a few notches. Now I was really feeling the strongest ones, with each one causing my body to jerk with movement. My breathing was shallow and I was gasping for air when the very strongest pulses fired. My palms and chest were sweaty, and I also felt a pool of sweat on my back. Now with each cycle, I was getting closer and closer to actually going over the edge. And since the lowest pulses were much higher than before, I didn’t have as much time to recover. I looked at the timer again – 210 seconds. I did some quick math in my head and realized that in just another 30 seconds I would be at the four minute mark – and the pulses would get even stronger. I so wished that I would cum and end all of this, but I just wasn’t there. I was aching to reach down and grab my cock. I so wanted to provide the stimulation that I needed to finish this. In a word, I was in agony.

“Four minutes,” Ashley said.

Now the pulses were even stronger. The very lowest one was almost the intensity of the strongest one when I first started this test. There was virtually no rest now between pulses, since even the weakest one was strong enough to cause my body to move. The feeling to ejaculate was getting stronger and stronger. I was no longer coming down from the edge – I just stayed there, almost ready to go over it at any second. At that moment, I looked up at Beth, standing there between my parted legs. She wasn’t looking down at my cock as I would have expected – she was looking up at me, directly at my face. And she was smiling. And as this cycle of pulses started again, I knew that this would be it. The pulses built up in intensity, my back arched, my fists clenched, the muscles in my legs and buttocks tightened. I finally shot my load of cum into the condom. Then another, and another, and another. Once I finally started to cum, each pulse sent another wave shooting into the condom. The pulses continued for a few more seconds, until the girls noticed that I had finished and had nothing more to give. And then the pulses stopped and the test was complete.

“All done, Jim,” said Beth, “you did well.”

I felt the fingers of her gloved hands peel off the condom from my still-erect cock. As I watched, she emptied the contents into what looked like a lab beaker.

“In case you’re wondering, we’re supposed to measure the amount of your ejaculate.”

Beth now turned her attention back to me and unfastened the cock strap that had been in place throughout all of the tests. I immediately felt the skin loosen as it was released from its tight bondage. My balls were no longer being held out and away from my body by the strap. I now felt them dangling free again. Next she disconnected the wires that connected the probe in my ass to the small metal box. Once they were disconnected, she slowly withdrew the probe from my ass.

“There you go, you don’t have to worry about that thing anymore.”

Beth and Ashley now unfastened the restraints holding my legs in place at the top of the leg supports. Next they unfastened my wrists from the exam table. They gently lifted my legs out of the supports and carefully lowered them while helping me to sit up. I was now finally free.