S1·E27 Dude of the Living Dead

The whole mall becomes infested with zombies. Jen has a giant zit on her forehead, and only the gang, Ron, The Clones, and Darth are left. The Clones go first because of their stupidity. Ron and Darth both act surprisingly more heroically than usual, and both sacrifice themselves to save the rest of the gang while fighting off many zombies. They find out that Starr is alive too and Jude comes up with a plan to kill the Zombies. It works for a while but fails later. The group gets bitten, Jude and Starr are left, they kiss, and then Zombie Jen pops her zit, and Jude pukes in Starr's mouth again. Jude wakes up and finds that he is dreaming. But when he goes to the mall that morning, he sees that Jen has a zit on her forehead and screams in horror.