Saturday Morning Breakfast Cereal, a Webcomic of science and inappropriate humor, has a snarling dare of a shirt for you. 

From the artist: 

The general smiled. "No," he said. "Hunting tigers ceased to interest me some years ago. I exhausted their possibilities, you see. No thrill left in tigers, no real danger. I live for danger, Mr. Rainsford. I live for grizzly-boom tennis."

What better way to let anybody who may be staring at your well-formed chest know that you do not dick around.  One look at this t-shirt and they’ll know that you came to do just two things: chew gum and ride a grizzly bear while batting at dynamite. 

Looks like you’re all out of gum.  [Buy it]