Mavis and Clavis were the geriatric movie critics Kenan Thompson and Kel Mitchell played on Nickelodeon's sketch show All That throughout the nineties, a running parody of the TV critics Gene Siskel and Roger Ebert. Tollin and Robbins, the company behind Kenan & Kel, put its logo at the end of those broadcasts, which is why this old end-of-show sign-off gag circulates under their name. The bit outlived the show: short meme uploads and soundboard rips turned the dozy farewell into a handy way to announce an ending anywhere.