Animals don't know how to use their words to express their disapproval, fear or anger, which is why preschool teachers never give animals any gold stars for properly sharing their feelings.
But they do know how to express themselves in one very impactful way- the warning nip.
This scary quick moment of lashing out tends to make humans stop pestering them and go away, and while it's not always funny when you're on the receiving end it's always funny to watch someone else get nipped.
Man, I wish I could nip at people who are annoying me without winding up in jail...
-Via Boing Boing