Also, Leonard and Penny try to prove Sheldon wrong after he says that he and Amy are a "superior couple."Amy and Bernadette accuse Penny of being a "buzzkill after she gets an email from work during their Vegas weekend.Meanwhile, the guys try to invent something cool, but only come up with new ways to procrastinat.
When Wolowitz seduces Penny's friend and takes over her apartment, Penny sleeps on Leonard and Sheldon's couch.
A train trip to San Francisco takes a major detour when Leonard (Johnny Galecki), Sheldon (Jim Parsons), Wolowitz (Simon Helberg) and Raj (Kunal Nayyar) discover that beautiful sci-fi actress Summer Glau ("Terminator: The Sarah Connor Chronicles") is onboard.
Things begin to look up for Leonard when Penny makes a surprising revelation on her second date with Stuart.
Meanwhile, Sheldon tries to learn how to be funny and Raj tries to work on his "game" before talking to girls.
Sheldon tries to relax after he is forced to take a vacation.
Leonard and Amy take an unexpected road trip to Arizona to pick up Sheldon.