More beef for Baker Mayfield ... this time the Browns superstar is getting into it with Arian Foster -- blasting the ex-NFL RB for being "too cool to show any personality."

It all went down on Twitter this weekend ... when a video of Baker dancing his face off caught Arian's attention.

"Your QB could never," the Cleveland Browns official account tweeted.

"*would never," Arian responded.

Mayfield saw the shade from the former Houston Texans superstar ... and went off.