I was just reminded today of a good joke concerning grammar I heard a while ago:

Why you should never end your sentences with a preposition:

Harry was getting along in years and found that he was unable to perform sexually. After putting it off for some time, he finally went to his doctor. The doctor tried a few things, but in the end, nothing seemed to work. So the doctor refers him to an American Indian medicine man.

Shortly after Harry's arrival, the medicine man says, "I can cure this." He throws a white powder in a flame, and there is a flash with billowing blue smoke.

Then he says,"This is powerful medicine. You can only use it once a year. All you have to do is say '123' and it shall rise for as long as you wish!"

Harry then asks, "What happens when it's over, and I don't want to continue?"

The medicine man replies: "All you or your partner has to say is "1234", and it will go down. But be warned," He said gravely, "it will not work again for another year."

Harry rushes home, eager to try out his new powers and prowess.

That night he is ready to surprise his wife, Joyce. He showers, shaves, and puts on his most exotic shaving lotion. He gets into bed, and lying next to her says, "123."

He suddenly becomes more aroused than anytime in his life, just as the medicine man had promised. Joyce, who had been facing away, turns over and asks,

"What did you say 123 for?"