You Promised

Paulie, a parrot fluent in English, is captured by scientists who are impressed by his ability. They promise him that if he helps them, they'll return him to his long lost owner. That night, Paulie overhears a scientist saying on the phone that they aren't going to return him and that he's now property of the institute. To get revenge, Paulie pretends to not understand English at the presentation.

Example of:
Language Fluency Denial