For all you who love the word "squee", in the webcomic Sheldon, it's the signature sound of Flaco the Lizard, who, in spite of that being the only thing he says, is often the smartest character in the strip.

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Here's the first occurance of Flaco "squee"-ing, apparently not with joy. The hat he wore for most of his first year had to do with his sidekicking for Arthur the Duck when he plays cowboy. And Arthur calls him 'my son' because of the origin story where Flaco hatched from an egg Arthur had mistaken for an abandoned duck egg and sat on himself. It's not supposed to make sense, it's a daily comic with a talking duck in it, okay?

And being in a webcomic, of course he has a t-shirt (or squee-shirt).