Dean steals someone’s backpack and acquires this blue broad plaid shirt. It’s a little bit too small for him in the arms, but he makes do.
Brand: American Eagle
In We Need to Talk about Kevin (8x01), Dean is wearing this shirt when he gets out of the truck that gave him a lift to Louisiana and he wears it while resurrecting Benny.
In Reichenbach (10x02), this is the shirt that Dean is wearing in the funny picture on Crowley’s phone.
Fate: My guess is that as soon as Dean made it back to Rufus' cabin and found his old clothes, he ditched this too small shirt.