Super Bowl Selfie Kid Ryan McKenna Slammed by Cops During Arrest, Video

Ryan McKenna, once famous for snapping a pic with Justin Timberlake at the Super Bowl, stands accused of striking a cop during his allegedly drunken arrest ... but new video shows cops tossing him to the ground pretty hard.

The clip, obtained by TMZ, shows 18-year-old Ryan with multiple cops around him as they try to detain him -- they're struggling to get his arms behind his back.

After the attempts to cuff him don't work ... you can see one of the deputies yank him by the leg, flipping him down on a concrete floor. Even after the brutal takedown, Ryan kept his arms tucked to his chest, instead of putting them behind his back.

TMZ broke the story ... law enforcement was called on the eve of this year's Super Bowl to a CPK in Naples, FL for a report of a man who was drunk and hitting his friend.

According to cops, Ryan and a 15-year-old boy got into an argument, and things escalated to the point where Ryan aggressively pushed their table and started shouting obscenities at the boy's GF.

In their report, cops admit putting hands on Ryan to calm him down, but claim he yanked their hands off his chest. Deputies then tried to detain Ryan, which is apparently when the video begins.

Cops said Ryan was taken to jail and booked for felony battery on a law enforcement officer and 2 misdemeanors -- resisting arrest and obstruction of an officer.

BTW, Ryan's mom Tracy told us her son was NOT drunk during the incident ... and instead was just joking around with his friends, trying to be funny by pushing the table.