f'nar / F'Nar / fNAR / FNAR / F-Nar / F-nar ...
When you do something stupid just because you felt like it and no one asked you to.
He threw his pizza in the trash for no apparent reason. It was still good.
She started crying in the middle of class for no apparent reason. No one knew why.
He ran out of the house for no apparent reason. He just came back 10 minutes later.