Flea HATES the Boston Celtics with the red, hot, fiery passion of 1,000 suns -- and when we saw the Red Hot Chili Peppers star at LAX ... HE WENT NUCLEAR on Beantown!!!
Oh, we should mention he's a die-hard Lakers fan ... if you couldn't tell by his throwback Magic Johnson shirt.
"I just think the Boston Celtics SUCK ASS," Flea proclaimed, "They're like the Satanic bottom of the basketball world! They are the shadow side."
It didn't stop there ... Flea reached way back into the rivalry to throw even more shade at the Celtics.
"Magic Johnson owned Larry Bird in college, owned him in the pros ... more championships, smoked him in college -- it's a simple fact."
We asked Flea if he'd like to see a Lakers vs. Celtics series in the NBA Finals -- and he went even HARDER!
"That would be thrilling. I'd like to see Lonzo dunk right on Jason Tatum's head!"
So, how do people in Boston feel about that? We got Mark Wahlberg out the other day, and he's already counting on the Celtics and the Boston Bruins to make it a clean 4-team championship sweep this year.
Of course, Boston teams are pretty dominant over L.A. right now -- the Red Sox beat the Dodgers in the World Series and the Patriots beat the Rams in the Super Bowl.