Law of Fashion 3: The Proper Uses of Sleeveless Shirts

In a Post-9/11 World, there are exactly two acceptable reasons for a man to wear a sleeveless shirt outside of his own home or the Olympics:

1.  The sleeveless shirt is an undershirt and is not visible.

B.  The man wearing it is, at that very moment, on stage acting in a play that takes place between 1923 and 1957.