This issue has variants.
Any comedy strip drawn by Hilary Barta gets automatic points from me; he's one of three modern artists I can think of with a Mad-quality combination of goofiness and manic energy (the other two being Kevin O'Neill and Flint Henry).
The first of many Charles Atlas parodies in which Mac becomes various Marvel characters.
Parody of the traditional self-defense book ad.
Gruenwald credit revealed in Carl Potts' blog:
Joke letters from Lisa Glynn, John Voskamp, Lewis Long, Orson Keyes, Jennifer Majewski.