I remember a few years back when Electronic Gaming Monthly did one of their April Fool's Day cheat codes (I think this one was that you could unlock Sonic and Tails in Super Smash Bros. Melee by getting ten kills in Cruel Melee), and Nintendo Power took a potshot at them in the next month's issue, saying something along the lines of "We pride ourselves on being honest with our subscribers and not tricking them with false information" or some crap like that.

As an interesting side note, so many people were angered by the April Fool's Joke that EGM held a contest where people were to send a videotape of them getting ten kills or more, and they'd win a copy of whatever game of the month they had that month. (I think the highest was over 20....and with Jigglypuff, no less!)