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
by AzraelNarianErnee September 19, 2013
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A black up plan can only be observed.

"What the hell, you're 2 weeks pregnant?!? Where's my boxing gloves."
by bpiau2728 February 4, 2012
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