Leonard is selling his share of the time machine and everyone is giving him offers below what he paid due to depreciation. He is also selling the rest of his collectibles and his friends argue and bid over the price.

Sheldon and Leonard are playing 3D chess which is a sequential game.

Raj and Sheldon partake in a series of juvenile tit-for-tat exchanges.

Raj trades Sheldon his limited edition Green-Lantern lantern in exchange for Sheldon's service as a wingman.

Leonard bids on a movie prop and ends up winning. He pays the amount he bid so this is a first-price auction.