When a customer walks in with a "Tommy Boy" poster signed by Chris Farley, will it have Corey saying holy schnikes, or does it belong in a van down by the river? Meanwhile, Rick tries not to slip up when making a deal on a pair of snowshoes used in World War II. Then, Rick and Corey get a blast from the past when they go see a hand cannon from the 1600s. Can they hit their target, or will it blow up in their faces? And later, Chum analyzes a block of graphite used in the Chicago Pile-1 nuclear experiment. Will this chain reaction be a good one, or will it result in a meltdown?