Craziest one I have ever saw (that has not already been mentioned) would be a sloth (species was not specified) while not the craziest thing I have seen all the other more outlandish things (Honey Badger, Anteater, Mid sized cats, Zebra, etc) A sloth I feel would still be a pretty bad pet as I feel their lifestyle is pretty hard to recreate in captivity since most people do not have giant tropical trees in their house or yard and even if you say had a tree in your yard, how would you feed the sloth? It would be high up in the trees and never come down except the rare occasion to go to the bathroom and the since these kinds of things seem to happen mostly in the U.S and Europe the tree itself probably could not be digestible for the sloth.