Yes, it's pretty adorable when penguins wobble around like little men in tuxedos. But we are increasingly learning that there is a dark side to the Antarctic creatures.

Penguins callously steal from their buddies. Penguins will happily attack humans, and use ice to their advantage when they do. And penguins will do this:

Not cool. True, the penguin who was knocked off the ledge landed in the water, so it probably wasn't injured. But don't think for a second that prankster penguin wouldn't have sent his flightless friend tumbling down onto something harder if the opportunity presented itself.

So the next time you are overcome with the urge to hug a penguin, remember this video. And watch your back.