Mooning the principal is such a classic prank. Watch Harold, Stinky, and Sid risk their academic careers in this hilarious clip from Hey Arnold! episode "Full Moon":
More Splat: Hey Arnold 20th Anniversary Memories w/ Craig Bartlett | Hey Arnold! | Nickelodeon Animation Studio!
Watch all your '90s Nickelodeon favorites on The Splat, your late-night destination for your favorite childhood Nickelodeon cartoons and live-action shows! The Splat doesn't question football-shaped heads, but embrace them - along with Reptar bars, a Big Ear of Corn, orange soda, and even slime for Pete (and Pete's) sake. Make your slime-covered Nickelodeon childhood dreams come true every night at 10pm ET/PT, only on TeenNick USA! #TheSplat!
Additional source: Hey Arnold Wiki.
Follow NickALive! on Twitter, Tumblr, Google+, via RSS, on Instagram, and/or Facebook for the latest Nickelodeon and The Splat News and Highlights!