Phineas and Ferb - Season 3 Episode 21 Bullseye!

When Lawrence heads out to attend a speaking engagement on antiques, he unwittingly finds himself participating in the L.O.V.E.M.U.F.F.I.N. Pageant of Evil against Dr. Doofenshmirtz and Rodney. As a special host oversees the proceedings, Perry is tasked with monitoring the situation, but Lawrence gets hit with Rodney's "Make-Everything-Evil-Izer", and is crowned the supreme leader of L.O.V.E.M.U.F.F.I.N. Meanwhile, Candace is determined to bust the boys but doesn't realize that the object she's looking at is not theirs. Across town, the boys are playing a giant game of darts.