Quote Originally Posted by Throbert McGee
I nearly crapped my pants from laughing so hard
Я чуть на обосрался от смеха. It's kind of rude though

You could ease it off but not much by replacing обосраться with наложить в штаны

Anyway, we don't usually speak like that if we want to say that we laughed really really hard. We have a set phrase for that - лопнуть от смеха

Я чуть не лопнул от смеха

Also there is this phrase - смеяться до коликов/боли meaning that you'd been laughing so hard that it started hurting