In 1971, National Lampoon magazine published an especially biting parody of Mad magazine. (That's the cover, above, painted by Spider-Man artist John Romita).
The main point of the parody is how unfunny Mad had become. Sample joke: You Know You've REALLY OUTGROWN MAD When... you find richer sources of humor in everyday things, like rocks.
Someone posted the entire thing here.
One of the most memorable parts of the parody was an overly mean-spirited spoof of Dave Berg's Lighter Side cartoons. Mark Evanier writes about the time a comic-book fan re-created one of the cartoons with the real Berg at a convention. Berg was unaware of the parody. Very funny.
