Logan Paul got in a physical altercation with a man outside an L.A. hotspot late Wednesday night ... slapping a heckler upside the head after he called the YouTube superstar a "p***y."
26-year-old Logan was waiting outside Nightingale in WeHo when a bunch of autograph seekers came up to him and started asking about his rumored fight with Mike Tyson.
When LP ignored the questions, one man called him out and said, "Are you a p***y, or what??" ... before trying to walk away.
That's when Logan aggressively approached the man ... getting in his face and shoving him before smacking him in the head.
The crowd is audibly shocked ... with several people gasping and saying, "Oh s***."
Logan's friend and "Impaulsive" podcast co-host Mike Majlak jumped into action ... pushing and shoving the heckler backwards before security came in and bear-hugged the guy away.
Majlak urged Logan to go into the club, but both guys were able to calm down and even joke with each other as Paul waited for valet to bring his Polaroid camera from his car.
Of course, Logan has been facing off against much bigger and more talented competition recently ... going 8 rounds with Floyd Mayweather back in June.
What's bizarre -- Logan maintained a smile throughout the whole incident ... but it's clear the altercation was pretty tense.
Logan eventually gets reunited with his beloved camera and heads into the club ... but accidentally drops it on his way in.
As for the heckler, he was later let go from security and stormed off in the opposite direction.