Future Hall of Famer Tony Gonzalez knows why Cam Newton is targeted by the hardest hitting players in the NFL -- 'cause he's got a big mouth.
After Sunday's 30-20 win over the Cardinals ... the Panthers star QB complained about the refs ... saying he didn't "feel safe" after hits he thought shoulda been flagged ... weren't.
Gonzalez -- who took his fair share of big hits during his 17 year career -- says Newton makes himself a target because of his cockiness.
"If I were him, I wouldn't do all that Superman stuff ... but that's his style," Gonzalez says.
"When you see stuff like that and you're a player, and you're going against a guy who's brass and kinda cocky, you're gonna want to give him a little extra juice."