​SCRIPT

An old couple enters a restaurant.

W: 　Are you ready to order?
M:    Yes, a steak for me, and a cup of vegetable soup for my wife.
W:   Certainly.

The couple finishes their meals and leaves.
Five minutes later, they come into the restaurant again.

W:   Oh, hello again, can I take your order?
M:   Oh yes, a cup of vegetable soup for me, and a steak for my wife.
W:   Oh I see, but why didn't you order them last time?
M:   Because we have only one set of false teeth.