The anatomy professor to student: "What part of the human body expands when energized by eight times?"

She blushes and stammers: "The, the ..."

"False, the pupil!" replied the professor. "And you, dear young lady, I would advise not to go with too high expectations in marriage."

The teacher to Peterchen: "Peter, which one of you stole from my apple tree apples yesterday?"

Peter: "Teacher, I can not understand anything in the last row here."

"We want to see it," the teacher says. "Come immediately to the front and sit down at my place. And then you ask me a question."

They change places.

Since Peter asks: "Teacher, who has slept with my sister yesterday?"

Replies the teacher: "Peter, you're right here behind you really does not understand ..."