Definitions by Brian Landis

kentucky tuck 

tucking the male anatomy underneath and in between legs in order to resemble the female anatomy.

The kentucky tuck is when a guy takes his balls and penis and tucks them underneath and in between his legs in order to make it appear as if he now has a vagina. At that point, the guy yells "check out my beav woooohoooo"

kentucky tuck by Brian Landis December 31, 2006