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The name for the tan lines left by wearing your sandals or flip flops too much in the summer time or in a warm climate.

Though commonly mistaken as an abbreviation for a "hillbilly tan", it is actually named for famed New Orleans mixologist and radio host, Bill DeTurk, who is known to commonly and proudly sport these tan lines.
Dude, check out my billy tan. These are the most amazing lines I've ever seen.

Whatever, don't act like you've gotten sun, you can't even show off your billy tan yet.
by captmrwill August 02, 2009
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