I'm trying to remember the details of a legend I read years ago - and I don't even remember which body of folklore it came from - about a hero with a herd of cows, all of whom had legs on one side longer than the other so that they could graze on the side of a very steep hill.
My initial guess was Finn McCool, but a cursory search of the best-known Finn legends doesn't reveal any lopsided cows; my next guess is one of the semi-modern American tall tale heroes - but Paul Bunyan is the only one I can remember offhand, and he's not the one. It's also possible that I misremembered this entirely, and there never was such a legend or tale...
Edit: it appears that this is A Thing in several parts of the world! The three that have been reported so far - the wild haggis, the dahu, the hillside gouger/ousel/dodger/etc. - all seem to be of the April Fool's joke or tourist prank variety; now I'm curious whether there ever was an "authentic" legendary occurrence. (Since the concept itself is patently ridiculous, it occurs to me that, even if a reference turns up in a 7th-century Irish illuminated manuscript, it might have been a joke even then... but at least it would be a really old joke.)