April Fool's hoaxes like the Grand Canyon Egyptians, PT Barnum's Cardiff Giant, other hoaxes about giants who were in the Earth in those days [sic], and other amusing and bemusing hoaxes.
It was inside of a giant ice cube that was inside of giant chest deep freeze with a glass door padlocked on top. You could clearly see large areas of its skin, complete with follicles and reasonably human-looking hair, but all of the bits that would have been really difficult to get realistic-looking beyond suspicion -- face, genitals, and finger and toe nails -- were shrouded in clouds of bubbles in the ice.

Not long after I saw it it "disappeared," allegedly because authorities were after the owner for unlawfully exhibiting human remains (or some such), but what they probably really were after him for was fraud. Regardless, its disappearance only added to the mystery.
Finally it was exposed as a made-to-order latex dummy that even went up for auction on eBay in 2013.

Ice Man, sans ice
Of course when I saw it I was in the Fox Muldur "I Want To Believe" frame of mind, so I was looking for the one detail the rest of the world had overlooked that proved it was genuine. From this remove, I'm still amazed but amazed that he pulled it off. I don't know how many times he re-froze the thing but when I saw it all of the cloudy bits of ice were positioned to perfection, which gives me to wonder whether he froze it repeatedly until it came out right, or if he knew some secret to cause it to appear cloudy in just the right places, ... of if he just got lucky.
In any case, it was one of the most intriguing hoaxes I've ever seen.