At a girl's college dormitory, dates were permitted only on Saturday
night.
One young man showed up on a Tuesday evening, explaining to an
older woman in the lobby of the dorm that it was imperative he see a
certain young lady immediately.

"I want to surprise her. You see, I'm her brother."

"Oh, she'll be surprised all right," said the woman.
"But think of how surprised I am! I'm her mother!"