LOL, I knew a cat like that once.

She (a vicious female Siamese) lived in a remote rural area where mail delivery came by car, and she would lie in wait behind a large spirea bush. The mail carrier learned quickly to wear a heavy glove to stuff the mail into the box, as "Sweetie" would leap out and attach herself to his wrist. The nasty thing also attacked each and every visitor to the home. Her owners lived in fear of her, but she had saved the life of their young daughter, and so was revered. She never once attacked that child, but unmercifully clawed the parents and older daughter. I still have an ugly scar on my forearm where she attacked as I tried to give the younger child a soft drink.