Listen folks, I’m running out of names for shirts, so you have to put up with me naming things after my own childhood. This shirt is green and blue with a small red and yellow stripes running through it too. The stripes are horizontal. It does up with buttons. It has two flapless breast pockets and is lined with white/cream colours material at least along the button-hole line.
In Safe House (11x16), Sam wears this shirt after they’ve dug up the graves and discovered that they’re not dealing with a ghost. He keeps it on until the end of the episode.
In LOTUS (12x08), Sam wears this shirt when they’re back in the Bunker trying to figure out who Lucifer’s latest vessel is. He is wearing it for Crowley’s visit, but has changed when they start planning how to get close to Lucifer now.
In Unfinished Business (13x20), Sam wears this shirt at the very end of the episode in the Bunker, when he confronts Dean about his behaviour as of late.