I'm not as dumb as you look

While waiting in front of my building for a friend to pick me up for lunch, a guy walked past me. He looked like he hadn't shaved in a few days or washed, for that matter. He was wearing a t-shirt, sleeves cut off and down both of his arms, as far as his wrist were multiple tattoos, including one of a naked woman and another of a dragon. That was just on his left side.

His shirt read "I'm not as dumb as you look."

If his shirt is right(and how could it not be?) I must be one stupid looking dude.