Justin Blackmon -- NFL Rookie Pleads Not Guilty to DUI

Former Oklahoma State badass Justin Blackmon insists ... he didn't drive like a drunk lunatic last weekend -- pleading "not guilty" in court yesterday to DUI.

According to the arrest report, Justin was pulled over early Sunday morning in Stillwater, OK for driving 60mph in a 35, and swerving into oncoming traffic. When the officer approached the vehicle, he detected the odor of alcohol.

According to the officer, Justin had red watery eyes and admitted to drinking before getting into the car.

The officer administered a field sobriety test and, after an abysmal performance, Justin was placed under arrest for DUI. When he got back to the police station, Blackmon blew a .24 (three times the legal limit).

Interesting -- Blackmon was recently drafted by the Jacksonville Jaguars, but still hasn't signed with the team. It's unclear how the arrest will affect negotiations, but there are reports the Jags will low ball him now.