The Fake Laugher

What do you do about a situation with someone who's either 1. laughing too long at something that's not remotely funny or 2. fake laughing?

The Andy Gibb meeting went OK, but at several junctions, he was laughing, so hard at seemingly nothing, that I did raise an eyebrow in concern. I tended to wonder if the laughter was even real.

Example--

Me: I can't but help notice your rings. They're gold. Very nice jewelry. Me, I'm more of a silver person.
Laugher: Bwahahahahahaha, Nate you're so funny.
Me: Well, I just like sterling silver actually.
Laugher: Bwhahahahahhaha, you're killing me. Gosh, you're funny.

At one of these awkward laughter fits, I started to burst out with laughter, too. Only I wasn't laughing with him.

It just was so uncomfortable and completely weird that I laughed really hard, too.

At one point, because he was laughing so hard at something that was not remotely funny, I re-imagined a really funny joke Seinfeld said, just so I could laugh along with him. Man, what the people in the coffee house who were eavesdropping might have been thinking--cringe.

And no. He was NOT laughing because he was nervous. He appeared very confident, which makes this whole thing weirder.

What gives?