Sesame Street Clips that scared me as a kid

Courtesy of Boing Boing, where they felt the same way. This first one with the orange singing was really scary:

This one was more funny, but it still bugged me.

I swore up and down that Mahna Mahna was from Sesame Street, while friends of mine insisted it was from the Muppet Show. Turns out we both were right. This first clip is the one I remember from childhood:

This one came much later: