By the way thank you OP for this thread. Downplaying and making light of the sexual assault of men is so widespread, so ubiquitous, threads like these are important in raising awareness.
I don't recall when I started taking this more seriously myself, but I was guilty of that too, until recent years at least. Laughed at prison rape jokes/TV gags, only took "violent" male-on-male rape seriously as rape, etc.
I now remember at least two incidents where a male acquaintance related their assault in my presence. Both were over ten years ago (one was near 20 years ago now, geez). One guy was in a gaming chatroom and told his story to the group, about a woman he didn't like forcing herself on him, he might have been drunk. It was so long ago, almost two decades, and I really can't remember any details or how we reacted. I think he got some sympathy, but also jokes or jeers. Like just "lol sucks to be you bro", probably. I can't remember though. >_<
I feel even worse for the other incident though. It was over a decade ago and involved co-workers. A female co-worker basically got a male co-worker drunk at an office party, and raped him. The male co-worker and I got along well and we kind of buddies, we'd crack jokes, roasted each other all the time etc. But this time he got pretty serious and he confided in me over chat messaging about what happened. I don't recall what I wrote back, but I think I would be ashamed of it if I read it today. I'd like to think I was supportive, but if I'm being realistic and honest, I probably cracked shitty jokes and... fuck. Wish I could go back and apologize to that guy.
Well, don't want to make this about me. But this goes to show why topics like these are so important, mostly for people to have a space to share their stories of course, but also to educate idiots like my younger ignorant self. I hope it helps some people open their eyes.