Years ago, we were doing a bout of chastity, I think I was at about week 3 and was really needing to cum, I couldn't concentrate while attempting to work, was looking at way too much porn, couldn't get to sleep at night. So we made an agreement if I was to break my agreement, i'd spend the entire day masturbating, cumming, then getting hard again, masturbating and cumming until I was unable to get hard or ejaculate. Sounded fun, so decided to do it. By the fourth orgasm, it was starting to wear thin, and enjoyed it less, by the 6 or 7th one, was almost on the verge of painful, not so much cumming, but the physical friction.
I think I got to 10 by the end of the day (which i'd done many, many times in my youth), couldn't get hard, didn't ejaculate anything.. perhaps a slight drop of clear cum, but could still feel some orgasmic pleasure. The next few days was a very different situation, my cock was very painful to touch and weirdly blew up like a balloon, which took the entire next day to go back down. I assumed it was fluid retention or something, but dreaded to thought of having to go to hospital, so a mild ice pack saved me. My wife and I always have fun with this kind of thing, but we took this one too far.