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

Penny ruins the cushion of Sheldon's seat on the couch and he brought it to Penny's dry cleaner. However, he doesn't trust her dry cleaner because he also makes keys.

Describes the role of Athens as a trading city in the Mediterranean, famous for its olive oil and innovations in pottery style and decoration.

Susan doesn't have the money to buy an item she wants, so she negotiates with the store owner, offering her items she has, in return for the item she wants.

Stringer Bell learns about product elasticity and then explains it to the gangsters he is in business with.