buttsauce
1)On Postal 2 when you add certain cheat codes the "Postal Dude" will say "buttsauce"

2)When a girl is getting buttfucked and the guy cums in her ass and some happens to leak out.
"that bitch in the 'sexygangbang.com' porn is just leaking major buttsauce! look at her, she loves it!"