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1.
When a penis gets stuck in a vagina during coital interactions, as if the penis got vacuumed by a Hoover Dirt Devil.
Julie was notorious for blackholing her victims into submission.
by Nicholas Kumar December 05, 2011
 
2.
A game commonly played in college and the military where participants try to get their opponent to look directly at their asshole.

Typically, a participant will try to surprise their opponent by hiding somewhere bent over with their ass cheeks spread. When the person walks into the unsuspecting place he/she is overwhelmed by the sight of the orifice.
Our blackholing game is on this month! I'm up 4-2. I blackholed Jim real good when he walked into his dorm last night. I was standing on his desk bent over and he nearly collapsed when he turned the light on.
by iwasjoe December 31, 2012
 
3.
Dropping all forms of communication with someone you can't stand.Usually done without prior warning.
In networking, black holes refer to places in the network where incoming traffic is silently discarded (or "dropped"), without informing the source that the data did not reach its intended recipient so...
Dude 1 : Dude I don't know whats wrong with my girlfriend, she refuses to see me, she won't take my calls and she unfriended me on facebook as well!

Dude 2 : Dude, she's blackholing you.
by kbirinder January 11, 2011