If you've never seen the opening theme for Reading Rainbow, go ahead and prep yourself with this (it's only 48 seconds).
Now, if you're not very familiar with the music of the Doors (or at least "Back Door Man" and "Peace Frog"), this probably won't work as well for you, but trust me, Fallon gets this one right:
[The Doors Sing "Reading Rainbow" Theme (Late Night with Jimmy Fallon)]
I've written my share of parodies, and the hardest part is finding that perfect balance between leaving enough of the original alone for people to enjoy the reference, and changing enough of it to make people get the joke. It's a hard thing to do. This is done about as perfectly as it gets.