The theme song itself was also pretty catchy. "Hey, it's Lamb Chops Play Along! So join the kids, and play along!"
"Funny Aneurysm" Moment: In one episode, Lamb Chop tries to convince Shari that she has pneumonia so that she'll stay home with her (Shari is unconvinced). Shari Lewis would die of pneumonia on August 2, 1998, while undergoing treatment for uterine cancer.
Crowning Moment of Heartwarming: From that same episode mentioned above, Shari and Lamb Chop spend the whole day together (since Lamb Chop didn't want to be away from Shari at all). Towards the end, Lamb Chop finally realizes that people need time to themselves but claims she can't think of anything that she likes to do on her own but with Shari's help, makes a paper chain of things she can do by herself. Using the paper chain as a metaphor, Shari tells Lamb Chop "No matter how far apart we are, we'll always be linked together." Watch the scene here (starts at about 5:42 in the video)
Shari's whole relationship with Lamb Chop, Charlie Horse and Hush Puppy was one big heartwarming moment. Other ventriloquists and their puppets act like partners, Vitriolic Best Buds, etc., but Shari was a loving, nurturing mother to her puppets, and as crazy as they could be, they were her devoted children.
Fridge Horror: The idea that people would be stuck singing a song absolutely forever purely on accident.
Fridge Logic: The idea that people started singing "The Song That Doesn't End" without knowing what it was when the song BEGINS "This is the song that doesn't end"...
Nightmare Fuel: To some people, the puppets look creepy enough to give you nightmares.
In one episode, Hush Puppy enters a sweepstakes to win a bike but winds up not winning in the end and learning that losing is a part of life. Maybe not that sad to an adult, but for any kids who had to learn that same thing, it may bring back painful memories of going through that experience.
In the episode "Peer Pressure," Lamb Chop gets kicked out of the "in-crowd" of girls at school because her new denim jacket is (literally) yesterday's fashion. Like the above example, it's sad for any kid who's gone through a similar experience, especially because it's one of the rare times that feisty little Lamb Chop is ever shown crying.
Shari Lewis' death counts as a real life example.
Speaking of which, she recorded this song for the spinoff Charlie Horse Music Pizza after she was diagnosed with cancer. Have tissues beside you while listening to it.