He wants to get closer to you, and him wanting to be called uncle is his way of doing it. If he really is a good person, even though you may not personally know him, you may warm up to it and one day call him uncle. Sounds a little like you're taking this a little bit too far, but I've never had my uncle move in with me...

Just start callin him "uncle bro" and invite him to your xbox and beerpong parties for some real bonding. It's not a bad thing to get to know your uncle.

And tell your aunt to make you a god damned pie. And make it apple.