A built-in waterfall is a slang term for a well-lubricated vagina. One that is very wet and moist. One that has been aroused and may be expecting company.
Her built-in waterfall was inviting
A Mississipi Waterfall is the act of pissing on a relative
Mom smelt like piss for a week after my brother gave her a mississippi waterfall
When in the shower you ejaculate on your partner and it mixes with the water than you watch the semen trickle down to her kankle
hey my girl might be fat but atleast i get to see a westchester waterfall everyday
When a female ejaculates so hard her pussy fluid squirts up your chest from your waist.
Last night I fucked a girl so hard that her pussy reverse waterfalled me.
When someone has diarrhea and defecates on a naked girl and it runs down over her breasts
I just had a Tijuana waterfall all over some chick.
A Salty Waterfall is a waterfall in which a female uses her vaginal cavity to suck up seawater, and then regurgitate it into a man's mouth while eating her out.
"Hey man, that girl you're talkin' to right now? Yeah, she gave me a salty waterfall at that party last week!"