Teachers with their students are like parents with their children - we find things funny that no one else does. What is hard to convey are the facial expressions, body movement etc that go along with the words - that is what makes the situations truly comical.
Mrs. _____ I have to go pee. - said by dancing child.
Well go then. - replied teacher with urgency as she did not want to clean up the floor.
Child comes back and announces to class with a smile on his face.
Hey everyone - that was a good pee!!