Maskless Man in Grocery Store Screams F-Bombs in Clerk's Face, Gets Booted

This guy unleashed his anti-mask fury on a poor Smart & Final employee -- flipping out like a maniac, but he changed his tune real quick when cops showed up in force.

The maskless man's meltdown happened in Paso Robles, CA -- a normally chill town known for its wineries -- and everyone in the store probably needed a drink after witnessing this public freakout.

According to reports ... the guy entered without a mask, so the female employee you see in the video gave him one, but he refused to put it on.

When she followed and demanded he wear it -- as required by California state order -- he decided to make a scene, screaming obscenities at the top of his lungs ... RIGHT in her face. Maskless too.

He was a real tough guy ... incredibly aggressive, and even lunged toward her -- but watch how quickly he piped down in the face of cops.