In Addams Family Reunion (1998) Uncle Fester has a dangerous chihuahua named Butchy who can transform into a horrific were-chi that lives off human hair.

Fester chose "secret commands" which he believed no one could guess to instigate the transformation. To turn Butchy into a were-chi you said, "Here Boy!" and to turn him back into a harmless pooch, you said, "Sick 'em!"