A person who appears innocent, cute, completely without the ability to do harm. This "fluffy bunny" is actually capable of extreme carnage and evilness if provoked. Derived from Monty Pythons Holy Grail see Killer Rabbit of Caerbannog.
"He cheated on his fluffy bunny girlfriend, and she took a baseball bat to his truck and his head when she found out. He is still in a coma."