I was in my mid-late twenties and was spending the night with an older man (early sixties, I have a bit of a silver daddy fetish). He was the more dominant type and I'm more submissive. I got to his house and we immediately went upstairs and took our clothes off. He was in control and had me wear a blindfold while we sucked each other's cocks. After a bit he switched positions and focused on sucking my cock until I shot a load in his mouth.
Having just shot a very intense load I was snapped back to my refactory period and was no longer turned on by what was happening. This is exactly what he was going for and while I was still blindfolded we started to make out so he could share my load. I could feel the familiar texture and taste of cum in my mouth but I've never tasted it that soon after getting off. It felt disgusting but I figured if I could handle it while being horny then I might as well go with it.
It didn't stop there. Next he took me over to a couch and tied me to it with my ass in the air. Again, if I were horny I'd be craving a cock in my ass, but at this point I wasn't so sure. Either way, if he wanted to fuck me then that's what I was there for. He fucked me until he got off and even though it was far less enjoyable for me than usual, I was still happy to oblige.
He made me cum a few more times that evening without cumming himself. By the time we went to bed I had completely lost interest in sex. At some point during the night I was woken up by him sporting a rock hard erection. He didn't have to say anything, I knew he wanted to fuck me so I got in position and let him use me to his satisfaction. After he shot his load we both laid there naked and fell asleep.
This is what I would consider the opposite of a top not letting his bottom cum. By having me cum it became a completely different experience where I was fully aware of being used for his pleasure while not feeling any pleasure of my own. Even though I didn't feel pleasure at the time, I still think back on it and have an overwhelming desire to be used again. The pleasure I've gotten from that "spank bank" memory is far more than I would've gotten had he not forced me to cum.