One fine day in the Sunday school, the lady teacher asks the pupils what kind of medicines they know and what they are used for.
Amanda : Tylenol
Teacher : Very good! And what is it used for ?
Amanda : It is used for headache.
Christine : Nytol.
Teacher : Excellent. And what it is used for ?
Christine : To help you sleep.'
Now it is little Johnny's turn.
Jonhhy : Viagra.
Teacher : Johnny, what is it used for ?
Johnny : I think it can be used for diarrhoea.
Teacher : Who told you this ?
Johnny : Nobody, but every evening Aunt Susan tells Uncle Sam - "Take a Viagra, maybe that little shit will get harder."