Similar to Sheldon's distressed Superman t-shirt only without all that distressed stuff. This is the clean, classic Man of Steel logo using the classic Man of Steel colors. Long story short: it's classic. You can purchase one just like it from the Amazon link below.
Featured on The Big Bang Theory episodes
S08 E04: "The Hook-Up Reverberation" S08 E13: "The Anxiety Optimization" S12 E06: "The Imitation Perturbation"