A ghetto back up plan.
A black up plan can only be observed.
"What the hell, you're 2 weeks pregnant?!? Where's my boxing gloves."
Having tentative plans with a person of color.
Steven: Hey do you want to go to the driving range later?
Blake: Yeah sure, but I thought you were playing ball with Montel?
Steven: I did, but he's just my black-up plan.
A Secondary plan that is either very sketchy or requires questionable methods
"oh hey dude how are you gonna do that"-Person 1
"im switching to my Black-up Plan"-Person 2