After the Tonight Show, Cella's work was shown on Dick Clark's TV's Bloopers & Practical Jokes under the name Len Cella's Silly Cinema, a moniker that Cella despised.
United States Practical Shooting Association | Practical Magic | Practical Fishkeeping | Old Possum's Book of Practical Cats | TV's Bloopers & Practical Jokes | The Practical Joker (Star Trek: The Animated Series) | The Practical Joker | Licensed practical nurse | Radio Yerevan jokes | Practical Wireless | Practical Kabbalah | Practical Color Coordinate System | Oxford Centre for Ecclesiology and Practical Theology | Old Jews Telling Jokes | New British Beetles - species not in Joy's practical handbook | "Medicinal Fried Chicken" includes several jokes about Pope Benedict XVI | Dog's don't tell jokes | Cyclopædia of Practical Medicine | 1000 Jokes |
He went on to write for NBC TV's Bloopers & Practical Jokes (Robert Klein segments), two seasons of Robert Klein Time for the USA Network and four seasons of the Disney Channel's The New Mickey Mouse Club where he was nominated for two CableAce Awards.