Two deaf people get married.  During the first week of marriage, they find that they are unable to communicate in the bedroom when they turn off the lights because they can't see each other using sign language.
 

After several nights of fumbling around and misunderstandings, the wife decides to find a solution.  "Honey," she signs, "Why don't we agree on some simple signals?  For instance, at night, if you want to have sex with me, reach over and squeeze my left breast one time.  If you don't want to have sex, reach over and squeeze my right breast one time."

The husband thinks this is a great idea and signs back to his wife, "Great idea!  Now if you want to have sex with ME, reach over and pull on my penis one time.  If you don't want to have sex, reach over and pull on my penis...fifty times!"