Wiktionary
n. A project, activity or goal pursued as a personal favorite, rather than because it is generally accepted as necessary or important.
Wikipedia
"Pet Project" is the second episode of the first season of Disney's Teacher's Pet, and the second episode of the series overall. It premiered on ABC's One Saturday Morning in the United States on September 16, 2000.
Usage examples of "pet project".
It's damned hard, I tell you, to ignore a Nobel Prize winner when he comes into my office, hat in hand, to ask for funding for a pet project.
The way it stands, lobbyists can give money to a legislator's campaign at any timeeven as that legislator prepares to vote on their pet project.
Dale Ainsworth on Riverside Drive, a pet project of Keating's, done in Late Renaissance and gray granite, was complete at last.
Never saw one of them who wouldn't kill his or her own grandmother for unlimited grant money for their pet project.
You've put a quarter million into what you yourself termed your pet project, and you don't have a clue what this Stanislaski's up to.
She had looked at it for three minutes (having put off picking it up for three days while she scribbled in her note-book on her own pet project) and announced that the radiation was artificial, generated by a single projector that could be destroyed, and had thus solved the problem.
And the Bridge is Senator Wagoner's pet project, so he'll have to go slowly.
Mac has another pet project stuck in his head, and there's no way the Institute can afford to do it.