f'nar / F'Nar / fNAR / FNAR / F-Nar / F-nar ...
You do something dumb just because you felt like being a total idiot and no one told you to.
He kicked the door for no apparent reason. It was already open.
She screamed at the cat for no apparent reason. The cat was just eating.
He turned off the lights for no apparent reason. It was the middle of the day.