Some players are just so wacky that they could offer to do something that, were they a normal roleplayer, would be of great help to the GM, and everyone will react with such vehemence that you'd suspect they'd just about offered to launch a nuke.
I call my father daddy and I'm 22. I think its a southern thing - everyone in both halves (Texas and Arkansas) of my family call their dad daddy, grown or not.
I think it's more of an American Midwest thing. The American side of my family (I'm half-Russian, half-American) all comes from the Midwest, such as Missouri, and they all use Daddy.
I still find it a bit odd, no offense >.>