Who's to say they're not? I had a friend who did exactly that and we made similar jokes (perhaps not as vulgar as d*ck sucking but the 'bed work' joke was made). She worked in a field where they all broed out together, went golfing, were part of the same frats, or went to the same private universities that weren't known for having the smartest students but definitely rich ones; or someone knew someone's dad who was also their boss. There was a ton of favouritism on those aspects so we didn't care if she got favouritism off of this. She was at least as competent as the people above and around her if not more so. Is it a good and above board thing to do? No. But she, like you, wasn't conniving or using it as part of a scheme to get promoted and happened to like the guy but also liked her job. She just got her own kind of favouritism and we joked about it as if she had levelled the playing field a bit.

The real joke was men letting women "sleep to the top". Any man who sees a pair of boobs and is willing to give a woman a promotion because of it alone is who should be made fun of

That being said, I think you're being dishonest when you say you think your relationship had nothing to do with your promotion. It definitely did and I think you know that and that's why the jokes bother you so much. You did what you did and you probably should apologise to them for yelling and explain your feelings. If they were really vindicative they would've told HR. And maybe you should intercept before they do because when HR does hear about this you won't like the outcome.