Forum:Nerrrd! - Which Episode?

There is an episode where Lisa is brought on stage at school, I believe announced as having perfect attendance or something, and from the crowd we can hear a student (presumably Nelson) yelling "Nerrrrd!" I can't for the life of me remember which episode that was or find any clues online. Can you guys help me out? It's a running joke I have with my girlfriend and I'd love to be able to show her the episode again. Thanks!!!