I've had an interest in urethral insertions for quite a while. But, after a scare while doing something dumb (story for another time!) I've been extremely cautious and never tried anything beyond a few inches until recently. I first ordered some sounds via amazon, and that went smoothly (*). Feeling a little more confident I finally ordered some intermittent self-catheters.To assuage my fear of doing something dumb, I got a few of each size (12fr, 14fr, 16fr) "with insertion supplies". Basically, each one had a sterile drape, gloves, and a couple iodine pads. Great! I figured, having studied the proper technique and having read enough warnings here and elsewhere, what could go wrong?Errr... I just can't seem to get them to actually get into the bladder. At first I thought I felt it pass the sphincter, but no urine came out. I'm pretty sure that it's just the external sphincter. I tried keeping a gentle pressure, but it was as if it was a dead end. Just to verify, I went ahead and "let go" -- some urine came out the catheter, but most of it came out from around the catheter!Finally I tried to hold some light pressure on it while I "let go" -- maybe it would slip in while I was opening the sphincter? Here's where it got funky...The whole catheter started vibrating!!! I think the internal sphincter was spasming. Why? I have no idea. I've tried to do some internet research, but I can only find info on catheters leading to bladder spasms and I'm pretty sure that's different since a) it's still not in my bladder, and b) that's supposed to be painful while this was not.A couple times I saw some bright red blood in the end 1" of the catheter after I pulled it out. Although my heart stopped momentarily thinking I must've punctured something, no more bleeding was seen after that.What am I doing wrong? Any suggestions?-g(*) - Always intend the pun! Why waste a good pun, after all?