Hioooo? Hi-Ooooo? What is this?

Have you ever heard someone follow up a fairly lame joke with “Hi-oooo” (sounds like “Hi”, then an extended “o”)? What exactly does it mean, and how is it really spelled? I hope this makes sense.

My WAG is that they are attempting to sound like Ed McMahon from the Tonight Show with Johnny Carson. Or At least like Phil Hartman doing an impersonation of him.

I always assumed it was a reference to Ed McMahon from his tonight show days, this was one of his “signature sounds”, IIRC.

Ah, awesome, thanks guys. Now what is the proper way of spelling it (or as close as you can get)?

Hi-yo!

Is it pronounced “Hi-Yoooo”? It always sounded like “Hi-ooo” to me.