This is a great symbol, and makes a great t shirt.  Vintage print, so it looks like you just got it from the past.  Interestingly enough, this script was rejected by studio after studio until Robert Zemeckis's movie Romancing the Stone was a commercial success.  Just more proof that most movie executives are at best humorless robots.

Anyway, this symbol is great, and really easy for people to not understand.  

By the way, this shirt is a weird off blue that I really couldn't color match.  Like a sky blue with a touch of turquoise.  Be aware the color is not quite what is posted here.  

By the way, as proof that anyone can gain fame, here is a link to a Christopher Lloyd (Emmett "Doc" Brown) fansite.
He actually has a pretty interesting career both in front of and behind the camera.