"Up Penny Lane" joke

One day, a teacher in a high school class was administering a test, and she noticed that four pupils were missing.

The first one came in.

"Why are you so late?" the teacher said to him.

"Sorry, miss," he said. "I''ve been up Penny Lane."

She told him to go sit down.

Then the second pupil came in.

"Why are you so late?" she said to him.

"Sorry miss," he said. "I''ve been up Penny Lane."

She told him to go sit down.

Then the third one came in.

"Why are you so late?" she said to him.

"Sorry miss," he said. "I''ve been up Penny Lane."

She told him to go sit down.

Finally, the fourth pupil, a girl, came in.

"I suppose you''ve been up Penny Lane, too, then?"

"No, miss," she said to the teacher. "I am Penny Lane"