Sam has a blue shirt just like this that is introduced in S4. This shirt is red and grey striped, with diamond shaped snaps. The breast pockets have double pointed flaps that do up with two snaps each.
Brand Information: Lucky Brand. RN 80318 CA 07558 Style 7MW2140JAS1
In A Very Supernatural Christmas (3x08), Sam wears it from their first meeting with the Carrigans through to killing them.
In It’s The Great Pumpkin, Sam Winchester (4x07), Sam wears it when studying the contents of the hex bag, and when reading about Samhain in the motel room.
In The Monster At The End Of This Book (4x18), Sam wears it to Chuck’s house after Chuck has his vision about Lilith’s visit. He keeps it on for the rest of the episode.
In Good God Y’all (5x02), Sam wears it when they are visiting Bobby in the hospital.
In I Believe The Children Are Our Future (5x06), Sam wears it when he and Dean test the joy-buzzer on the ham, and then visit to the joke shop.
In Mannequin 3: The Reckoning (6x14), Sam wears this shirt when he goes to investigate the scene after the sex-doll kills the guy Sam thought he had saved the night before. He keeps it on until the ghost is truly dispatched.
In ...And Then There Were None (6x16), Sam wears this shirt at the beginning of the episode at Bobby’s, and also when they go to the cannery at night to hunt the monster.
In Meet the New Boss (7x01), Sam wears this shirt once they get back from meeting Death, and Sam tries to convince Dean not to give up hope on Cas. He keeps it on until the end of the episode.
Sam is still wearing this shirt as Hello, Cruel World (7x02) opens, and until Castiel disappears into the water.
In Time After Time (7x12), Sam wears this shirt starting from the stakeout with Dean when Dean disappears until the end of the episode.
In Plucky Pennywhistle’s Magical Menagerie (7x14), Sam is wearing this shirt at the beginning of the episode when Dean talks to Frank on the payphone.In Trial and Error (8x14), Sam wears this shirt when he and Dean go to the Cassity farm and get jobs. He keeps it on until Carl is killed and we see the other Cassitys arriving for the funeral.
In Blade Runners (9x16), Sam is wearing this shirt when Crowley calls the Winchesters for help. He wears it until they get Crowley back to the Bunker.
In Stairway to Heaven (9x22), Sam wears this shirt from when he and Cas leave to go find Josiah, until the end of the episode.
Sam continues to wear this shirt in Do You Believe in Miracles (9x23) for the entire episode.
In The Executioner’s Song (10x14), Sam wears this shirt when he, Dean, and Cas are in the Bunker and discover who the likely next victim is for Cain. He wears it until after Dean kills Cain.