I know George Perez did a couple illustrations here & there in the late-70s/early-80s for National Lampoon. I was at Quimby's in Chicago and they had a new book, National Lampoon's Big Book of Love. In this book is the Perez illustration that accompanied P.J. O'Rourke's essay, "How to Drive Fast on Drugs While Getting Your Wing-Wang Squeezed and Not Spill Your Drink," from 1979. In following up on this in a Yahoo! search, I found the article along with multiple uses of Perez's contribution to the article.

www.nationallampoon.com/../02_howto.asp

(Vu: On the same website, they also have another George Pérez piece: ACTION GOLF Nine Holes of Hoopla, written by John Hughes. Warning: the art and article is a little adult, so link with caution.)