A young woman is teaching a class of primary school kids, and she has to bend over to write on the blackboard...

1st boy: Hee hee hee

Teacher: What are you laughing at?

1st boy: When you bend over to write on the blackboard miss, your skirt starts to lift up!

Teacher: Your a naughty boy! Get out of this classroom! You are banned from school for 2 months!

(teacher is back to writing on the blackboard)

2nd boy: Hee hee haa haa

Teacher: What are you laughing at?

2nd boy: When you bent over miss, I could see your knickers!

Teacher: Your a VERY naughty boy! Get out of this classroom! You are banned from school for 6 months!!

(teacher has now dropped the chalk on the floor! And has to bend right over to pick it up!!..)

3rd boy: Hoo hoo haa haa haa!

Teacher: What are you laughing at?

(boy is already walking out of the classroom..!)

Teacher: And where do you think you are going?

3rd boy: After what I've just seen miss, I think my schooldays must be over!