In The Big Bang Theory, Sheldon is seen wearing a graphic t-shirt in nearly every scene (that he's not in pajamas, a suit, or a tango outfit).
Most of these t-shirts can be seen as a statement for the esteem that Sheldon holds for the image. Most usually they are comic book logos or homages to science.
One shirt that I can't figure out why he would be proud to wear, the television test pattern associated with the old cathode ray sets, and signing off in the middle of the night.
What about this seems particularly compelling to want to wear it on a t-shirt - especially considering the feelings he expresses for the subjects of the other shirts?