hootenanny

That makes sense. I guess I was equating it more with "party animal" or just "fun guy." :-P

I suspect "that guy is a hoot" comes from someone "hooting with laughter" and means that guy is funny or that guy makes me laugh.

hoot: verb

(of people) to make a loud noise of laughter or disapproval
Example: They hooted with laughter.

Wikipedia does say the word was used like thingamajig in the early 20th c. So could be.

And thanks for calling attention to it; I'm adding it to my Shindigs list.

I wonder if this is the root behind the phrase "that guy is a hoot!"?

a gathering at which folksingers entertain often with the audience joining in, popular in the late 50s and early 60s, also referred to simply as a "hoot"
Are you going to the hoot tonight?