From those wacky gals and guys at Overheard in New York, this classic.
And from Nancy V.:
A family is at the dinner table. The son asks his father, "Dad, how many kinds of boobies are there?The father, surprised, answers,
"Well, son, there's three kinds of breasts. In her twenties, a women's breasts are like melons, round and firm. In her thirties to forties, they are like pears, still nice but hanging a bit. After fifty, they are like onions."
"Yes, you see them and they make you cry"
This infuriated his wife and daughter so the daughter said, "Mum, how many kinds of 'willies' are there?"
The mother, surprised, smiles and answers, "Well dear, a man goes through three phases. In his twenties, his willy is like an oak tree, mighty and hard. In his thirties and forties, it is a birch, flexible but reliable. After his fifties, it is like a Christmas tree."
"A Christmas tree?"
"Yes, dead from the root up and the balls are for decoration only."