This shirt is very similar to Sam’s S9 Grey-Blue Plaid, but unfortunately for me, the plaid patterning is different enough, that I have to make a whole other entry for it. Listen, I like Blue Plaid, I do, but how many blue plaid shirts does one character need? In anycase, this plaid appears to be blue and appears to do up with snaps.
In Hibbing 911 (10x08), Sam changes into this shirt after Donna learns about vampires and he and Dean can drop the FBI facade. He wears it until the end of the episode.