http://www.theguardian.com/music/2013/nov/21/show-us-your-favourite-band-t-shirt

Apparently, it's wear your band t-shirt to work day.

Anyway, mine was the Hole tour t-shirt I bought at their Brixton gig in 1995. Brilliant gig. I think it's in a pile of old clothes in my old bedroom at my parents' house.