As far as I know, Diff’rent Strokes was really the show that began the trend of Very Special Episodes – which arguably peaked and receded during the final season of Blossom.
A lot of things can be ‘Very Special’ however, and Diff’rent Strokes liked to cast a wide net. Have you ever heard of The Bicycle Man?
Gordon Jump, (the boss from WKRP in Cincinnati & The Lonely Maytag Repairman,) played a bicycle shop owner who was quite interested in cutting Arnold a deal – in exchange for his pants. It’s surprising, for an early ’80s sitcom, how far they went with this Child-Molester warning.
It might have been a little more effective without the laugh track though.
Here’s the crux, but you can find both episodes dealing with the subject on youtube: