4x8 - Codename: Kids Next Door

The Delightful Children From Down the Lane decide to give their birthday cake to the winner of the annual Tubathon race and everyone is eager to go for it. No one is more eager than Numbuh 2, who plans to use his old tube, Betsy, and "farfegtubing". But are the Delightfuls keeping their word about the cake or are they luring the competitors into a trap?