Forget taking over McKinley High.

Glee's Kurt and Mercedes are desperate to be the most popular members of their Glee club on Tuesday's all new episode (titled "Bad Reputation," 9 p.m. Fox).

"Our reps have reached terminal velocity," Kurt Hummel (Chris Colfer) laments in an all-new clip (watch above), as Mercedes (Amber Riley), Tina (Jenna Ushkowitz) and Artie (Kevin McHale) look on. "What does a C-lister do when they're about to fall off the radar screen? They cause a scandal so extreme they can no longer be ignored."

But Glee club's ditzy cheerleader, Brittany (Heather Morris), is determined to outrank the two.

"I don't know why I've only made fourth on the 'G-list,'" she says. "I've made out with, like, everyone in this school: girls, boys, the janitor. I need to do something to get into the top three."

Find out who tops the G-list -- and catch guest appearances from Olivia Newton John and Molly Shannon -- when Glee airs Tuesday at 9 p.m. on Fox.