Thought I'd look for old Sesame Street clips that were freaky.
That creepy opera singing orange I mentioned before
http://www.youtube.com/watch?v=Z8TqOTe3ODc
Count to 12 with a bunch of rocks (ritual sacrifice?)
http://www.youtube.com/watch?v=C2zuez3VK1U
Count to 10 with a scary floating face
http://www.youtube.com/watch?v=vVktxm3p7gI
I'll probably think of more.