Chad Johnson says the NY Giants should be very careful on how they handle Odell Beckham Jr. -- because if they get on him too hard for the dog pee celebration, it's gonna mess up his head. 

Look, Chad says Odell is special ... and if going crazy on the field helps him dominate, so be it. The worst thing you can do is neuter him ... get it? 

We also asked if it's time to fire Marvin Lewis in Cincinnati -- after the team's 0-3 start. 

Chad not only goes to bat for his old coach, but explains why he's the best thing that's happened to the Bengals franchise in a long time.