look up any word, like donkey punch:
 
1.
A rather unique method of masturbation for males, whereas the male sits on his dominant hand until the blood flow decreases to the point that the hand has "fallen asleep", then using it to masturbate. Said to give much truer feeling of having another person pleasure oneself, instead of the older method of simply turning one's hand around to masturbate, which doesn't really work anyway. Or, so I've heard.
"Dude, don't touch that guys hand. He's all the time t'rowin' the Scary Uncle on his'self."
by Tío Espantoso October 28, 2005
 
2.
To jump across wooden logs over-top of water, some of which are spinning on rotating wheels, and do a backflip on to the other log, but then slip off of the next one.

Derived from SpikeTV's MXC in which a contestant pulled a "full-blown scary uncle" to get to the other log in a game called "Log Drivers."
Kenny Blankenship: Wow, Vic, I think that was a full-blown scary uncle!

Vic Romano: It was indeed, Kenny.
by Mehro March 29, 2005
 
3.
A classic pool move made popular in 2006. It's when you do a front flip into the pool and pull your pants down mid flip. The purpose is to land in front of someone and splash them. It's usually directed toward children or friends.
"Dude, I heard Tony scary uncled Chuck twice at the pool today. And he said he's gonna do it again!"

"Tony scary uncled every little kid at my pool today. Some kid's dad kicked him out."
by Royce da59 July 01, 2010
 
4.
1)The pediphilic uncle in every family unit that is a bit off and enjoys spending time w/ his nephews alone and unsupervised.

2)A extremely rare and difficult move practiced by participants of MXE
No Bobby, I don't want to spend the night at your house, you have a Scary Uncle.
by Samhain_Knight August 10, 2004
 
5.
The only position from which one can properly deliver a chili pie.
I put her into the Scary Uncle and then I gave her the ol' chili pie.
by Asyd309 April 23, 2005