This joke falls into the – “oops!” category:
A guy goes to see his grandmother and takes one of his friends with him. While he’s talking to his grandmother, his friend starts eating the peanuts that are on the coffee table, and finishes them off.
As they’re leaving, the friend says, “Thanks for the peanuts!”
The grandmother says, “You’re welcome young man. Since I lost my dentures, I can only suck the chocolate off ’em.”