I simply had to buy a tshirt while at Mammoth Cave, Kentucky last summer.
It's bright orange, has a big oval in the middle that looks like one of those country-code stickers on European cars that's been co-opted as tourist crap in the States.
Big, white lettering of 'KY', then in little teeny letters below it 'mammoth cave national park'.
I get the *BEST* double takes... especially on the West Coast, farther away from the state.
