This Munchkin polo shirt is themed for Munchkin. It has a silhouette of the Munchkin Man in gold on a black shirt.
The shirt-specific Munchkin rules (items #2 and #3 from the main board game description) are as follows:
3. The autograph of Steve Jackson, Andrew Hackard, or John Kovalic on the shirt gives you an extra +1 combat bonus per autograph, to a maximum bonus of +5.