Prevent Horizon

I have a theory.

The impetus for the Kool-Aid Man was a vision brought on by some thirsty guy listening to The Doors in the early '70s. 

Case in point: In "Break on Through (To the Other Side)," Jim Morrison sings, "Break on through/ Oh yeah!"

The Kool-Aid Man breaks on through (to the other side), then says, "Oh yeah!"