Crisco

Two boys were skinny-dipping and the one couldn't help noticing the size of the other's manhood, so he asked, "How did ya get it that big?"

The other boy responded, "Well I rub it down every night with lard."

Two weeks later they were back at the swimming hole. Once again, there was a comparison made, with no results.

The first boy said, "I did what ya told me. Every night I have rubbed it down with Crisco."

The other boy exclaimed, "Well, no wonder. That's shortening."