Oklahoma quarterback Baker Mayfield says he's soooo sorry for sticking the OU flag on the Ohio State logo after beating the Buckeyes on Saturday ... saying his emotions got the best of him. 

Mayfield's Sooners put the smack down on OSU in a 31-16 victory at The Horseshoe -- and bitter Ohio State fans are saying the flag move was straight up disrespectful (shoulda won then, huh). 

Now, Mayfield is apologizing for the move -- saying, "I didn't mean for it to be disrespectful" ... adding, "I got caught up in an emotional win."

Mayfield says the gloating should have been saved for the locker room and the utter display of dominance should not have gone down in the middle of the field. 

Is he right? No. That was awesome.