On my 60th birthday, I got a gift certificate from my wife. The certificate paid for a visit to a shaman living on a nearby reservation who was rumored to have a wonderful cure for erectile dysfunction.
After being persuaded, I drove to the reservation, handed my ticket to the shaman, and wondered what I was in for. The old man slowly, methodically produced a potion, handed it to me, and with a grip on my shoulder, warned, "This is powerful medicine and it must be respected. You take only a teaspoonful and then say '1-2-3'. When you do that, you will be more potent than you have ever been in your life and you can perform as long as you want."
I was encouraged. As he walked away, I turned and asked, "How do I stop the medicine from working?"
Your partner must say "1-2-3-4", the shaman responded. But when she does, the medicine will not work again until the next full moon.
I was eager to see if it worked I went home, showered, shaved, took a spoonful of the medicine, and then invited my wife to join me in the bedroom. When she came in, I took off my clothes and said, "1-2-3!"
Immediately, I was the manliest of men.
My wife was excited and began throwing off her clothes. And then she asked, "What was the 1-2-3 for?"
And that, boys and girls, is why we should never end our sentences with a preposition.