Well, my group doesn't do T-shirts, but there is considerable consternation over deciding who has to be the 'explanation dummy'. The ED basically has to stand there and react appropriately to whatever is being demonstrated on him. Thankfully, it only led to hospitalization once, when one of our friends, a genuine Kung Fu instructor, was playing a monk, and accidentally threw Joey through a sliding door while demonstrating a Knockdown Feat usage against the main bad guy. I think Joey talks just fine, I don't know what everyone was whining about.