A young fellow was about to be married and was asking his grandfather about sex. He asked, How often I should have it?" His grandfather told him, "When you first get married, you want it all the time, and will 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 his grandfather, "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."