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1.
When you cum on somebody's back and throw a sheet over them so it sticks and it looks like a cape.
He was forced to seek help from a psychiatrist after his obsession with supermanning got him into trouble with his latest girlfriend.
by wraftonstagboys June 19, 2011
 
2.
The act of lying face down, and placing arms in front of you, in a superman like manner.

No, it's not like planking.
Why would you even ask that?
What are you doing?
SUPERMANNING.
by ProSupermanner September 29, 2011
 
3.
A sex position akin to the missonary position, with the person on top extending their arms and legs and humming the superman theme.
S.C.: (Humming superman theme song)
S.K.: What are you doing?
S.C.: I'm Super Manning
by Nachington November 30, 2010
 
4.
urinating in a trashcan out doors. you need to be laying on top tof the can (it is easier if you are a man) with your willy dangeling into the can then after you are ballanced stick your arms out in front of you and your legs out behind you and let 'er rip..
john was arrester while supermanning in public because urinating out doors is illegal
by landon franz May 17, 2008