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adj. when someone's pants are so tight that the middle seam of the jeans get sucked into the buttcrack,clearly lifting and separating both cheeks.

Also, closely associated to, or may result from a whale tail.
That girl's jeans were so tight, not only did this girl have a camel toe, but she was rockin' a whale jaw in the back.
by Dr. Mantis Toboggan November 30, 2009
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