The Thanksgiving Decoupling - S7-E9
Continuity mistake: When Sheldon and Mike are drunk on the couch after Howard leaves, they are toasting with the beer cans. Sheldon has his in his right hand, but when Bernardette came in, the can is in his left. A little bit later, after he says "she's so tiny", the can moves back to his right hand.
Chosen answer: It does. The variable cleanliness of the cab and the habit of taxi drivers to engage customers in small talk would be too much for Sheldon to handle, and not an option for him.
Captain Defenestrator