A marijuana brownie that has been laced with the dealer's creamy cum. Only given to people who say "Yo let me get the brownie now and I'll pay you later."
A space brownie is southern street code for Pot brownies. This term came about due to the inability to discuss pot brownies in front of offical upholders of the law and because when you eat them you become very spaced out and relaxed.
"Dude! Naomi's got Space brownies at his place! Wanna go get baked?"