A guy goes into a restaurant and orders a plain bowl of lettuce. When it arrives, he stuffs it into his shirt. Then he orders another bowl of lettuce and does the same thing.
He calls the waitress over and orders another bowl of lettuce. "We're all out of lettuce. Will cabbage do?" The guys says, "I guess so," so she brings him a bowl of cabbage and he starts stuffing it into his shirt.
A guy sitting at the neighboring table is overcome by curiosity. So he says to the guy, "Hey, why are you stuffing cabbage into your shirt?" Guy replies, "Because they're out of lettuce."