yapper

noun

1. (slang)A person's mouth, especially one that gossips or talks too much.

   “Shut your yapper or I'll shut it for you!”

2. One who yaps.

   “If you want your pack to be a deterrent against burglars or muggers, forget about small dogs, yappers though they be. Focus on the larger breeds, particularly working stock with strong instinctual drives.”

   “I have to admit I would have a lot more tolerance for cell phone yappers on my one-hour train ride to and from work if they were actually learning — instead of yelling […]”

3. (abbreviation, alt-of, ellipsis, informal)Ellipsis of yapper dog

   “If you’ve got a yapper dog, take him somewhere else.”