Rinse & Spit is episode 10b in Season 1 of Rocko's Modern Life. In this episode Filburt needs a paitent for his dentistry exam, at first he tries to force Heffer into this but later makes Rocko the guinea pig as he reminds him that he saved his life when they were young and that Rocko "owes him one." Filburt accidentally mutates Rocko's cavity, and it goes on a rampage around O-Town.
Filburt chases Heffer around the neighborhood armed with pliers and Heffer runs to Rocko's house, hiding behind the sofa. Filburt arrives as well and asks Rocko if he would like to be his patient for his final dental exam. But Rocko tells him that his teeth are already perfect. When Filburt finally reminds Rocko how he saved him from a beating from a gang of bullies on the playground during their childhood, Rocko reluctantly agrees to take part in Filburt's exam. At the Academy O-Dentistry, Filburt inspects Rocko's teeth and comes across a tooth with a cavity. Filburt gives Rocko water to rinse his mouth off and spit it out into the sink. The turtle them performs an x-ray on Rocko's teeth by placing electrodes on the tooth with the cavity, angering the tooth as it tries to escape from Rocko's mouth. It uses the X-O-Matic to free itself and grow into a large tooth monster. Rocko tries to keep it under control, but to no avail. The tooth monster grabs Rocko and heads to the city of O-Town. Filburt tries to abandon his exam, but Dr. Hutchison, the teacher of the exam, reminds him that he now has to pursue the tooth monster, which the turtle complies to. He dresses as a tooth fairy and scales the top building of Conglom-O, where he confronts the tooth monster in top of the roof. When Dr. Hutchison's hook falls off as the tooth monster grabs her, Rocko tells Filburt to aim for the cavity (which he is secretly in despair of since Filburt is a terrible thrower). Filburt fortuitously tosses the hook to the cavity, which cause the tooth monster to drop Rocko and Dr. Hutchison on the roof and land down the ground below. Dr. Hutchison retrieves her hook and the tooth shrinks back to size. it runs in a can, and Rocko picks the can up and places his tooth back inside his mouth. Filburt gets a medal for his work, but his diploma is nullified due to his inept dental skills. Discouraged, Filburt walks away and sits on the curb of the sidewalk. Rocko comes to his side and coaxes him. Filburt tells him that he was never planning to be a dentist anyway, but a chimney sweeper instead (while singing a song of it as well). Rocko quickly cuts him off and tells Filburt to walk with him to get a soda, but this time, without a song. After the iris end, a talking foot named Gordon explain good oral hygiene to the audience right before riding away in a taxi cab.
Filburt: Isn't she cute?