Greg Oden's loss is someone's else's gain ... because the t-shirt the NBA star was wearing in his mug shot has instantly become the top seller for the company that makes it.
The "Ohio" t-shirt has the image of a man holding two middle fingers in the air for the "H"-- and is made by Lamp Apparel, a company based in Columbus, OH ... home of Oden's alma mater Ohio State.
TMZ Sports spoke to Brandon Fuss-Cheatham, one of the co-founders of Lamp Apparel, who says since Oden's mug was released ... their website's getting crushed by people trying to get their hands on the shirt.
In fact, the feeding frenzy on the $28 dollar tee has been so intense ... the Lamp Apparel website is struggling to handle the traffic.
Despite the boost, Fuss-Cheatham -- who played at Ohio State before Oden did and does know him -- says he's getting no joy from Oden's current situation.
He tells TMZ Sports, "I'm friends with Greg, so it's kinda weird that he'd be wearing this shirt when all of this happened. But he's a good guy and I hope things work out for him."