Joke reused from THE WEST WING
Pardon me for messing this up, but it's pretty similar:
A young Jewish man calls his mother. He asks, "How are you doing?"
"Not well. I haven't eaten in 38 days."
"You haven't eaten in 38 days! WHY?"
"I didn't want my mouth to be full just in case you called."
On The WEST WING, Donna tells this joke to Josh.
On STUDIO 60, Matt tells this joke to Harriet so she has a joke she can tell to a group of people giving her an award. Everytime she tries to tell it, she messes it up.
"What time is Recess?"