an imitation of the music that underscores adult film. Originally used as an introduction in IRC rooms and bulletin boards, it has evolved to include the physical act of sexual intercourse.

The phrase originally included, "*ding dong*", "Pizza Delivery", and "bwah-chicka-bwah-bwah" (in that order) as a representation of how a typical low-budget adult film would begin. It was later shortened to just "bwah-chicka-bwah-bwah".
Poster #1: *ding dong*
Poster #2: Pizza Delivery!
Poster #1: bwah-chicka-bwah-bwah!
Poster #2: LOL

You know what I'm sayin'! Last night I got me some bwah-chicka-bwah-bwah!
by Dwight (no relation) October 8, 2005
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