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1.
ACB
Afternoon Coffee Break

Duhhh! You know you want to take an ACB every week day after lunch! The most ideal, prescribed time for takin any ACB is 3:00PM (Mon-Fri). Not to worry if you feel like getting your caffeine fix early in the afternoon...Just call it an E-ACB (Early ....)
ACB time! Whos with me!! (Everyone says:MEEE)
by LuckyK August 03, 2012
 
2.
ACB
Attention Craving Bitch : A Female or Male who always wants attention. Typically they are annoying as hell.
Example 1
John: Dude, my girlfriend kept interrupting me while i was telling my story, to tell what she did.

Bob: She sounds like a big time ACB.

John: She is. >__<

Example 2

Lauren: Did you seen my new hoodie I bought, or what about my shoes. Did you like my new jeans too? or what about....

Mike: SHUTUP YOU Stupid ACB!!!!!
by BigBangBlunt October 23, 2011
 
3.
ACB
Short for "Anonymous Confession Board" that students at a certain university use; online confession board that is often abused by overly passive-aggressive students who don't know how to take jokes use to voice their childish opinions; online confession board which some students use to insult innocent students and to validate their meaningless existences; online confession board which many students who don't know the value of communication use to compensate for their inner selves; online confession board which help some students feel wanted by creating a false sense of community through insulting another human being; online confession boards abused by idiots who don't know understand basic problem solving; online confession board abused by idiots
"OMG! Did you hear that Tyler wrote shit about her on the ACB?"

"Fuck that shit. The ACB is stupid. It's what people use to create drama when they're bored."
by GetALifeACB May 04, 2008
 
4.
ACB
Mnemonic device for "Air Conditioner Booty": a woman whose buttocks, when viewed from the side, resemble a wall-unit air conditioner protruding from a house.
Holly's ACB was knocking peoples' drinks off the table last night.
by duct_tape_wallet December 19, 2005