My brother has one of the fattest, ill-tempered crotchety Chihuahuas I've ever seen. Many times I've walked past it and it come up behind me and tries to bite my ankles. Respect and love for my brother is the only thing that keeps me from punting that little pigdog across the front yard.
My aunt had a siamese cat like that. We were terrified of her (we were little kids). She would hide under furniture and when we walked by she would leap out and dig her claws into our ankles. What an awful cat!