I had been playing with plain water enemas for a year or so (not a fan of soap), and finally got around trying generic bisacodyl suppositories (the usual 10 mg dose, like Dulcolax) for the first time. About a day and half earlier, I had done a large enema (3 litres), so my rectum and probably a good portion of the descending colon was still completely empty, but I was curious about the suppo's general effects and inserted one anyway. For the first 15 or 20 minutes, I felt nothing whatsoever. After that, it felt like my bowels were a bit tense if that makes sense. Nothing uncomfortable however, I was laying in bed and actually dozed off for 20 minutes.
After an hour, I got bored (and somewhat disappointed) and went to the toilet, expelling only what was left of the suppository. Unsurprisingly, the tense feeling persisted, so I decided to have an enema to rinse out what was left of the Bisacodyl. This is where things really got interesting.
As soon as I inserted the enema tube, my colon was trying to expel it. This urge increased when I started to let some water flow in, after only half a litre it became unbearable. I ran to the toilet and quickly got rid of the water, followed by some fecal matter from the colon. Afterward I did another enema, and still felt the effect of the bisacodyl. This time I got 1.5 litres in before having to make a run, which then was expelled much faster than usual along with foul-smelling fecal matter that must have been way further up in the colon.
Now I'm looking forward to trying another one when I'm actually feeling a natural urge to go.