Don't mess with pro skateboarders -- just check out this insane video shot in Illinois this weekend, showing pro boarders Don Nguyen and Justin Figueroa unleashing fists of fury on a bunch of locals ... and someone even pulls out a KNIFE.
The fight went down Saturday at Asylum Skatepark in Lake Bluff -- the owner tells TMZ, Don "The Nuge" Nguyen and Justin "Figgy" Figueroa stopped by for a demo as part of Thrasher's Skate Rock Tour.
According to the owner, Nuge's team ruffled some locals' feathers when they requested the house DJ make room for his music instead ... and a massive brawl broke out.
After several punches were thrown, someone yelled out, "He's got a knife!"
Turns out the knife belonged to a local involved in the brawl -- and he tells TMZ, he took out the blade to help stop the fight ... but quickly put it away when he realized it would only make a bad situation worse.
The irony ... we're told locals involved in the fight are all big Nuge fans ... and still are ... their tempers just got the better of them.
Skateboard Clause In WNBA Contract
'I Know What's At Stake'
5/3/2013 4:00 AM PDT BY TMZ STAFF
Before Brittney Griner signed her fat new contract as the #1 overall pick in the 2013 WNBA draft ... she had to make a promise to her team -- I'LL TONE DOWN MY SKATEBOARDING HABIT.
"I agreed with the Mercury that I would only ride in a controlled environment," Griner tells TMZ ... "No tricks or hill bombing."
Besides being the most dominant female basketball player to come out of college in years, Griner is an avid skater ... who's been riding since she was a little kid.
"I know what is at stake, so I'll just be cruising. I'll get my adrenaline rush on the court."
Griner -- who's 6'8" and DUNKS -- caused a major uproar during her college career at Baylor when she broke her wrist while riding in a parking structure.
"Before that, I had never been injured," Griner said ... explaining, "[I was] going too fast."
"Once my basketball career is over though, I will be building a skate ramp in my yard, that's for sure."