Don't ask me why but this commercial scared the crap out of me when I was a kid.
I actually could never get past the psychedelic miasma and sinister voice at the opening and probably NEVER saw the commercial in it's entirety. The second that thing would come on the air I would bolt from the room.
As a result, Mr. Yuk stickers were VERY effective... I wouldn't go within ten feet of one because it reminded me of the commercial and freaked me out. Which you would think wouldn't have been a problem.... except that my sister decided to torture me by putting them places like the inside lid of our toy box and the inside lid of the chest where our picture books were stored.
Obviously, I got over my "Mr. Yuk" fears.... eventually. Wonder if I could have sued the Poison Control Center for emotional trauma?