Morning joke

Grandfather and grandson go fishing. Grandpa takes a beer a opens it and grandson asks him:
"Hey grandpa, may I have also one beer?"
Granny says: "It depands... Can you touch your ass with your dick?"
"No..."
So you can not...
After a week little boy has a birthday party and grandpa is late. There is a last piece of cake and he asks his grandson:
"May i have the last piece of cake please?"
"It depends... Can you touch your ass with your dick?"
Grandpa proudly says: "Yes, of course "
SO FUCK YOURSELF!!!