An indoor waterfall is an easy way to release urine when there is no bathroom in sight. To execute an indoor waterfall you must be wearing attire that you aren't afraid to let smell like pee. And you must double and triple check that there are no police in public because it is still considering indecent exposure. The ideal spot for an indoor waterfall is a water park, if executed properly you will have kids playing in it like its cotton candy.

Although a water park is a great place to execute this action, it has been done in grocery store parking lots, parks, and campus suites. Go into an indoor waterfall with the idea that you will be shunned upon if caught, but if you succeed you and your friends will have laughs for days.
(Waiting in a 2hr line)

Me: Jeah I have to pee!
Friend: Just go for it!
Me: Indoor waterfall?
Friend: Jeah I'll indoor waterfall it with you.

pssssss

Me: Alex your super drunk indoor waterfall!
Alex: Okay

pssssss

Me: This emo jerk behind us is such a goob!
Tim: Jeah you should release the beast on him
Sean: Indoor waterfall?
Derek, Tim, Alex: JEAH!
by deeemo October 7, 2010
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