Chad Johnson did his best Santa Claus impression last weekend ... gifting a $1,000 tip to a single mother waitress -- and the gesture was awesome.
TMZ Sports has learned the ex-NFL star was dining at Bar Louie in Tampa, Fla. back on Nov. 26 -- and after piling up a $102 bill, he decided to get super generous.
The former Cincinnati Bengals wideout added a $1,000 tip to his total ... and when his waitress, Kayla Ashby, went back to him to make sure it wasn't a mistake, we're told he revealed to her it was no joke.