This is used as a highly ironic response to somebody's last statement in a long line of statements, usually full of boring detail, about things that are only to do with them.
Such things as the tiny little facts about their life, lover, job, achievements etc that are only interesting to the person telling about them ... but to anybody else? Nope.
From the song of the same name "zip-a-dee-doo-dah, zip-a-dee-ay, wonderful feeling, wonderful day"
Kevin: Well I got this new bank account and no they don't charge me for checks but of course I had to personalize the checks so I got this photo of me brushing my teeth and photoshopped my name in my mouth K-E-V-I-N one letter on each tooth from left to right or from right to left so they are don't spell NIVEK of course so you know, right, so that everybody can see it's me by name but anyway of course I don't have the letters tattooed on my teeth in real life but who knows I might just do that because it's a statement about me and you know that's a good thing, anyway as I was saying I also managed to get that same photo on the Visa card that the bank gave me too which is really cool so then..
Chuck: Well, zip-a-dee-doo-dah. Life is wonderful, ain't it?