Disney's Teacher's Pet Episode Four - S01E04 - A Lick Is Still A Kiss

Leonard mentions to the cool kids that Leslie uses pink lemonade lip gloss with a hint o' mint, which he had learned from Spot, but that turns into a rumor that he had kissed Leslie on the lips. It doesn't get any better when Principal Stricker threats him (along with Scott later on when he defends Leonard) to be sent to the "School For Losers".