Lights off
Lights on

Summary

The guys discover that Penny is back together with her dimwitted ex-boyfriend, Zack. After they make fun of him, the guys apologize to him which he accepts upon receiving some Milk Duds. Zack joins them on their weekly trek to the comic book store, ditching Penny in doing so. At the store, the guys realize that Zack would be a great Superman for their Justice League group costume at the upcoming comic book store New Year's Eve costume party. They return home with a Wonder Woman costume for Penny. She initially refuses, but as no other girl is available to go, she finally agrees. The night of the party arrives with Howard being dressed as Batman, Raj as Aquaman (although he complains about it numerous times), Sheldon as The Flash, Leonard as the Green Lantern, Zack as Superman and Penny as Wonder Woman...

Episode Guide