Dead or alive?

I'm a kid.  I spend the night at my cousin's house and the next day we end up at some kind of community center.  I don't remember how the conversation gets started, but we end up in a heated disagreement about an uncle of ours, I'll call him "Uncle Walter."  She says he's alive.  I insist that he's dead.

We're smack in the middle of the it when we hear:

"Hello girls!"

It's Uncle Walter.

We just look at each other.  We can't believe how weird it is that he showed up at that precise moment.  We break down into helpless laughter.

"What's so funny?" he asks.

We don't tell him.