BCBB is an acronym for "Bowmp Chika Bowmp Bowmp". It is used on chat systems such as IRC (Internet Relay Chat). It's intended to mimic the stereotypical soundtrack for a pornographic movie, and is used to underscore real or imagined sexual innuendo.

Example:

<user1> user3 i don't want to hear about you bobbing on a navy ship
<user2> bcbb
<user3> ha ha, user2, stfu.

Y'know, if you log in, you can write something here, or contact authors directly on the site. Create a New User if you don't already have an account.