A horny young man went to a brothel... The lady at the counter asked him 
what his choice would be. The man wanted to know what was available. 
Madam, "On the first floor, we have the ex-models... they are all slinky 
and sexy... On the second floor, we have our ex-actresses...they are all 
buxom and beautiful... On the third floor, we have our ex-teachers.... 
they..."
Man, "Say no more! Lead me to the third floor."
Madam, "Are you sure... I'm surprised that you would prefer ex-teachers to 
ex-models and ex-actresses."
Man, "It's obvious, ma'am, teachers always make you do a thing over and 
over again, until you're perfect at it."