When someone gets drunk and throws up on a bar/restaurant table. In order to have successfully pulled off a four-sided waterfall, the person must have consumed such a large volume of alcohol that the liquid pours down all four sides of the table uninterrupted as if cascading from their mouth to the table, and finally down to the floor.
Friend 1: Hey guys! Check it out! Jon is throwing upon the table!
Friend 2: Dude, how much did he drink? It's totally spilling off the sides.
Friend 1: Looks like he made the Ole' Four-Sided Waterfall....
A beaver waterfall is when a woman lies down in the bathtub, places both legs on the wall, places her vagina underneath the faucet, and uses running water to masterbate.
Sheila was feeling very lonely after watching "Murder, She Wrote" so she decided it was time for a beaver waterfall.
When an intoxicated fun loving and amazingly hilarious guy asks a slightly intoxicated, fun loving, naked woman to bend over while he, who won't let go of his college fraternity days, takes puff from pencil joint, then pours ice cold beer down her ass crack into his welcoming mouth, holds the hit for so long that the small vein on his temple bulges out, and then he blows the hit out. The sequence may be wrapped up with a tongue dart.
An urban waterfall is a natural waterfall located in an urban area that has some man-made changes done to it, such as enclosing the natural creek above or below the falls into a storm sewer or box culvert or the construction of a bridge or road over the creek above the falls. The actual waterfall itself normally has not changed, just its natural surroundings have been changed by man.
Dundas Falls located in Hamilton Canada is an urban waterfall because Spencer Creek above the falls has been enclosed into a large storm sewer pipe as shown on this link:
http://www.conservationhamilton.ca/parks/visit/dundasfalls.asp
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