The barely-over-an-hour movie about the elephant with big ears. I don't even care for the movie that much, I didn't even like it as a kid. But it has one scene that absolutely held my attention, both then and now.
Pink Elephants on Parade
I'd never seen shit like this...
It was both terrifying and oddly transfixing to me as a kid. It's pretty much the original and defining Disney Acid Sequence (and is, of course, the example picture on that TVTropes page). It defies explanation and is completely out of place in an otherwise boring (and kind of racist) movie about... an elephant with big ears (though it does, in a roundabout way, inform our mute hero of his otherworldly power).
No more talk. Only madness.