The phrase was created from a hiphop/rap group DL2.
To throw a stack of money in the air like a shuriken. A stack is piled up on one hand and the other hand rubs off the money on the top of the stack until its all gone. The act of spraying money looks as if the money is being sprayed out of the hand.
Spraying money can be done by big time ballers and ballers. Big time ballers often use 100's and 20's where as ballers use singles.
Hold that stack spray that money in the air. - DL2
Kid: I wanna spray money but I only got a 20.
Old G: Change that 20 to singles then ull be spraying that money son.
Kid: Now I be ballin!