look up any word, like plopping:
 
2.
n. Large breasts. A Japanese slang term adapted from a transliteration of the term "boing" which, as we all know, is what good breasts do.
Dave: So much ii boin here at this anime convention, amirite Steve?

Steve: The only "boin" I see is attached to fat dudes, you blind weeaboo. Get some damn megane already.
by Estrella Muerta October 18, 2008
 
1.
Japanese slang term that means big breasts.
1. Hi Boin-chan
What did you just call me?
by SoHumHallelujah April 21, 2009
 
3.
-verb (used with or without object) to engage in the act of sexual intercourse or the conglomeration of two separate genitals. Commonly used to replace the f word so children who shouldnt be hearing the f word due to their young/virgin ears wont be corrupted. Usually spoken by realists.
Ex1: Danny, are u going to boin the "silly rabbit" tonight or not because if you need a ride to her house I will be off work at Bravo at 7.
by verbatim4ever March 30, 2010
 
4.
Synonymous with "to burn", used only when implying the use of marijuana.
Who wants wants to "boin" (some sweet nuggets)?
by Midnight Tokers April 09, 2006
 
5.
to land on
*ROLLS A 5*
Jordan: 1, 2 3, 4, and 5,
Awe shit, I landed on your boin.
Now what?

Breyanna: Who won the race?

Jordan: I dunno

Breyanna: CHARLIE DID
*gives jordan a charlie horse*
by breyanna and jordan =) July 10, 2008