A young fellow was about to be married and was asking his   grandfather about sex. He asked how often you should have it.         
His grandfather told him that when you first get married, you want it all the time... and maybe do it several times a day. Later on, sex tapers off and you have it once a week or so.         
Then as you get older, you have sex maybe once a month. When you get really old, you are lucky to have it once a year... maybe on your anniversary.         
The young fellow then asked, "Well how about you and Grandma now?"
His grandfather replied, "Oh, we just have oral sex now."
"What's oral sex?" the young fellow asked.         
"Well," Grandpa said, "She goes to bed in her bedroom, and I go to bed in my bedroom. And she yells, 'Fuck You!', and I holler back, 'Fuck You too!'"