Howard and Sheldon feud over a parking spot.
Read MoreWiFi Password
Sheldon changes the password on the WiFi.
Read MorePenny's Negative Externalities
A new part of the Roommate Agreement includes payments for all of Penny's bad habits.
Read MoreDinner Talk Externalities
Amy talks about tampons which upsets the guys.
Read MorePizza Free Rider
Penny consumes a pizza without paying because Leonard does not enforce property rights.
Read MoreArguments as a Negative Externality
Leonard and Penny are in a huge fight.
Read MoreNeighbors as a Nuisance
When Sheldon learns that the neighbors above their apartment will move out, he begins to list all of the negative externalities that they didn't produce.
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