warpenguin
Noun. A seemingly benign creature that becomes confrontational, even vicious, unexpectedly. They are famed for their potent wing-flapping dick-kick (or WFDK) attack, which they use because, well, penguins don't have fists.
"I thought he was cool until he went all warpenguin on me!"
"Did you see that warpenguin just WFDK that dude?"
"Did you see that warpenguin just WFDK that dude?"