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8.
An act of aggression that occurs "when fools need a beating, and you call your homies, and put in some work."
If you don't get yo' hands off my bitch, I'm callin' for black-up.
by Rihanna had it coming January 23, 2011
 
9.
To make oneself black in nature even if they have white skin
I need to black up before my 100m sprint.
 
10.
When the white boys don't work out, always have a back up blackman in mind (your blackup)
My boyfriend cheated on me at the party last weekend, good thing I have a blackup.
by buckeyefan52 March 24, 2012
 
11.
the traffic caused by a group of African Americans blocking the hall and preventing Caucasian students from moving to their next class.
Tom: Dude, why arent we moving?????
Andrew: Man this is the Math hall. This is probably the black-up from all those black guys who walk slowly.
by FlockaFlocka12 February 02, 2011
 
12.
When a white male cop pulls over an African American he needs to call in an African American female cop so that he does not get accused of racial harassment or abuse.
"Hey, Jeremiah, I was just in Miami and I saw three brothers pulled over by an old white cop. Lucky his blackup was shaking them down with her fat fingers or we could have filed a lawsuit for racial profiling."
by pitt_fresno May 08, 2014
 
13.
When an altercation occurs between two or more persons of non-European descent, a third party will call a relative or friend. Once the call is made, three or more vehicles will arrive instantaneously to render such assistance as needed to the caller.
Woman 1: "Bitch, don't you lay a hand on my fucking child!"

Woman 2: "That Hoe fucked my Man!"

Crowd that gathers instantly: "Oh snap!"

Woman off to the side: "Shit is going down, I'm calling for Blackup.", {on phone} "MMMMmmmmmHHMMMM~!"

Instantly, cars full of people appear. Scientists believe this phenomenon to utilize what they call "Black-Holes".
by Sexy Hitler December 29, 2009
 
14.
The secondary police unit that is called to the scene of a traffic stop where the driver is african-american and the location of the stop is in a predominately caucasian area
An african-american is stopped in a predominantly white town and the officer calls for a secondary unit as "blackup"
by cygnus_x11 May 13, 2009