Sexual Exhaustion
A high school English teacher reminds her class of tomorrow's final exam.
She also tells them that there will be no excuse for failing to show up, except for serious injury, illness, or a death in the student's immediate family.
A smart-ass jock in the back of the room pipes up and asks the teacher out loud, "What about extreme sexual exhaustion?"
The entire class has all it can do keep from breaking up, being barely able to stifle its laughter and snickering.
When silence is restored, the teacher smiles sympathetically at the student, shakes her head, and sweetly says, "You can write with your other hand then."