Wiktionary
loony tune
n. (context humorous English) a silly or crazy person.
Usage examples of "loony tune".
The grown-ups in your party weren't about to accept a loony tune like you as nominee, even for what was supposed to be a kamikaze run, without a sane moderate to balance the ticket.
More than anythin in the world, I wished I were not such a loony tune.
A loony tune, he decided as he stuffed the napkin into his pocket.
Hammer had always nurtured the unspoken fear that in the end, she would be taken out by a loony tune with a mission.
The ships that reported the message have been told it was a loony tune.