A signboard outside a restaurant said: "Eat as much as you can and let your grandchildren pay the bill."
A man entered the restaurant, ate as much as he could, and when the waiter gave him the bill he pointed to the signboard and said, "Don't you see; only my grandchild needs to pay for this bill".
The waiter replied, "But sir, this is not your bill. This is your grandfather's bill."
Cheers,
Paul (A.)