Referenced from the Chappelle Show when Wayne Brady was the guest. It is what you say before you want to whoop someones ass/take their money/commence some form of violence or robbery. Sometimes mistaken for 'brace yourself'...which is wrong.
(Whilst watching Chapelle Show)

Wayne Brady: There he is....BREAK YO SELF FOOL!
Man: AWW SHIT, IT'S WAYNE BRADY, SON!
*Wayne Brady shoots the guy down*

Rhyz: haha that's funny, BRACE YO SELF FOOL
Helena:.........you just killed it........just...no.....
by RIVERSIDE MOTHAF****KA September 4, 2010
Get the Break yo self fool! mug.