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
Get the mug
Get a Boin mug for your mom Nathalie.
Synonym for "Normie." Used to describe them, considering saying "Normie" is now a thing that normies, or rather, boins, now do.
Get this boin out of here
by Confetti-Throwing Puppet July 29, 2018
Get the mug
Get a Boin mug for your Facebook friend Zora.
-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
Get the mug
Get a Boin mug for your buddy Helena.
to land on
Jordan: 1, 2 3, 4, and 5,
Awe shit, I landed on your boin.
Now what?

Breyanna: Who won the race?

Jordan: I dunno

*gives jordan a charlie horse*
by breyanna and jordan =) July 10, 2008
Get the mug
Get a boin mug for your father Abdul.