I'd pay a large sum to get a particular friend of mine to learn that with her little monster lap-dog ;~D
They seem to think that because they have a chihuahua or a min-pin, what would be condemned as unacceptable aggression in a full size dog is somehow "cute" or "tough". It's unacceptable in any size dog, and it isn't cute, and it doesn't make the owner or his dog look "tough". It just shows that the owner can't or won't train his animal properly.
Some of those little guys are beyond redemption. :) (I love 'em all anyway, of course!)