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1.
unka tunka is the "relationship" between two people who've slept with someone in common.

unka-tunka adj. If A sleeps with B, and B sleeps with C, A and C are unka-tunka. Some uses also are directional with respect to time. In this rarer usage, if A went out with B before B went out with C, then C is disease unka-tunka to A, but A is not disease unka-tunka to C. Beware of unka-tunka 'trees.'
like it or not, you're unka tunka with your lover's exes.
by deminu March 02, 2010