Maycee Barber Nearly Forced To Fight Unhinged Lady In Parking Lot

Talk about messing with the wrong person ... a woman in Southern California nearly picked a fight with one of the baddest women on the planet, UFC star Maycee Barber -- and it's all on video!

TMZ Sports talked to 25-year-old Barber, the 4th ranked flyweight, and YouTuber/social media star Demi Bagby ... where the two athletes recounted the entire crazy incident.

Check out the clip for the full story, and what was going through Barber's mind (like how she'd have to call Dana White were she arrested) ... but the cliff notes go like this!

Barber, traveling from Las Vegas, says she made the 5-ish hour trek to Carlsbad, CA, where Bagby was with her husband ... as the group planned to hang out together and celebrate some good news that MB just received.

But, those plans changed when Maycee and Demi say a random woman ran out of her house (after 1:30 AM, mind you), straight for Bagby's car, and she refused to move.

"Please get off my car," Demi pleaded with the lady ... to which the woman said, "Move me."

Things just got tenser from there, with the woman saying ... "Don't touch me 'cause I could bust you in your f***ing face."

Around then, Barber stepped in ... but the lady didn't cease running her mouth, subsequently threatening both Maycee and Demi.

"I could beat both of your motherf***ing asses but I won't."

Fortunately for the woman, cooler heads ultimately prevailed (thanks to Maycee and Demi's self-control) ... and that's very fortunate for the face of the crap-talking woman.

Barber is 14-2 as a professional MMA fighter ... and has won 6 fights in a row, beating the likes of Jessica Eye and Amanda Ribas , amongst others.

Lesson A -- why you don't pick fights with strangers ... they may just be UFC fighters!