I bought gadgets from a number of vendors at a toy train show last weekend. The first vendor itemized my purchases on a preprinted receipt, figuring out the sales tax before totalling the tab. Then I bought a twenty-dollar item from another vendor and all he asked for was twenty dollars.

“No sales tax?” I asked.

“Nah, we’ll call it even,” he said, “unless you work for the state.”

I considered telling him that I did, in fact, work for the state, but couldn’t think fast enough to come up with a way that wouldn’t freak him the hell out.