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the girl or guy that is currently a) hoonbuping b) doing sexual favors or c) dating (which usually never happens) with your big in a fraternity or sorority.

Note: your big-in-law is usually in contact with your big more than you (the little) are.
little: "what's up big-in-law?"

little: "I haven't seen my big in forever.. he wasn't at pomping or toga toga toga.. he's prob at the big-in-law's dorm.."
by tucker123 December 06, 2010
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