2001
A small article in the April magazine advertised that Sega found a warehouse full of Sega Neptunes and were selling them off. There was a website listed where one could order a Neptune for $50. However, after one added it to their cart they were immediately directed to another web site that read "APRIL FOOLS!" and had a counter at the bottom of the screen showing how many people "fell" for it.
Read more about this topic: EGM April Fools' Jokes