During oral sex you gag so hard you throw up on your partner.
Last night I gave my husband a roaring waterfall.
Urinating on one's own scrotum, often by accident.
Steve's pants were too tight, and it was very hot out. He had to keep drinking water, so inevitably he wound up having to pee. He entered a McDonald's, and when he got into the bathroom, he realized he also needed to poop. So he sat down on the toilet, and as he let out his stream of urine, he did not yet realize the degree to which sweat had glued his scrotum to his shaft, and received a rock waterfall.
When one urinates through the legs of another person who is defecating.
Pisser: "Bro, I really gotta piss!"
Pooper: "Dude... I'm taking a shit"
Pisser: "Whatever bro, lets muddy waterfall!"
When you have a cold and you've wiped your nose so many times, the space below has turned red and hurts.
A: You look sad, are you alright?
B: Yeah, I've got a cold and I got a Waterfall Abrasion. It really hurts.
When one's balls are sweaty enough to create a trickle flowing down the gouch and dripping right before reaching the butthole.
Damn homes...it's so muggy out here my gouch waterfall could fill up a pint glass.
That gouch waterfall I dealt with all day made these boxers smell rank as fuck.
To have a 'Rocky Waterfall' is to simultaneously urinate while having a dump.
Example 1. "I was so desperate for a wee, that when I was shitting I pissed at the same time. It looked like a rocky waterfall."
Example 2. "I was desperate for some really kinky porn, so I looked up golden showers with scat. What I got can only be described as a rocky waterfall"
The feeling of a man’s semen dripping out of a woman’s vagina after sexual intercourse
After sex, my vagina becomes a complete Persian Waterfall.