Grape to raisin 

A testicle party trick. With scrotum exposed, one will grasp firmly either testicle, and say to the audience "see? grape!" He then pushes it through the grasp in his hand, only holding onto the wrinkled scrotom that was previously stretched tight around the testicle (the result resembling a hairy raisin), which is his cue to tell his audience "now it's a raisin!". Usually done while drunk and on ritilan. Originated in Bloomsburg PA in the mid-1990's

Who wants to see grape to raisin? And have you ever seen my grandfather's watch?

Grape to raisin by The real Kyda August 11, 2010