A boy and his grandpa

A grandfather is sitting on his porch having a beer when his grandson walks out and asks to try a sip. "Can your dick touch your asshole?" The grandpa asks. "No" says the boy. "Well, then you can't have any" says the grandpa.
The next summer day, it's hot out and the grandson is sitting on the porch eating ice cream. The grandfather comes out to sit with the boy and says, "boy it sure is hot! You mind giving your grandpa a bit of that ice cream?". "That depends. Can your dick touch your asshole?" Asks the boy. "Well, yeah it can" says the man. "Well then go fuck yourself" says the boy.