Heard a few years ago whilst flying a 747 from LAX to LHR:

Salt Lake Center:
"Airline 123, you bound for Vegas?"

Airline 123:
"Yup."

Salt Lake Center:
"You a [DC-]10?"

Airline 123:
"Yup."

Salt Lake Center:
"Well, I guess your passengers need a 10 to take home their winnings?"

Airline 123:
"Nope! Our passengers can take home their winnings in a Cessna 152."

Alan Murgatroyd
via e-mail