Twins

A woman gives birth to twins. At age 8, one twin notices that his brother is about an inch taller than he is, but doesn't think much of it. At age 10, his brother appears to be two inches taller, and naturally the shorter boy begins to get discouraged. When they reach the age of 12, the shorter boy is astonished to see that his brother is almost four inches taller than he is, even though they're twins!

So the shorter boy confronts his twin brother, asking, "How is it that we're twins, yet you're so much taller than I am? Is it something you're eating, or an exercise you're doing, or what??" The taller boy replies, "Well, I have a secret way of increasing my height." "I thought so," said the shorter twin. "What is this secret of yours?" The taller boy says, "Well, every night before going to bed I grease up my legs so they're nice and slippery, and then I sleep with my legs hanging over the end of the bed. Gravity pulls down on my legs, and since they are so slippery they ever-so-gradually stretch down toward the floor."

So the shorter twin does exactly what his brother told him, and does it faithfully every night. Yet when they reached the age of 14, he is dumbfounded by the fact that his twin brother is now a whopping six inches taller than he is! So he confronts him again and says, "You're still shooting up like a weed, and I'm not catching up to you at all, yet I have been doing exactly what you said...what gives??" The taller twin says, "Tell me...what have you been using to grease your legs up?" The shorter twin says, "Well, I've been using Crisco...it's the only thing I could find."

"Well, there's your problem right there. Crisco's a shortening."