Maybe he doesn't mean that as a joke, but the idea of making friends with that man makes her laugh. "Friends, with him? No, if I find my PPG, he'll have to watch what he says!"
What with Will's crew finding the brooch out in the water, it seems the case must've popped open, and a tide must've come up and dragged some of the items under. Some probably dug in to the sand, though. And damnit, it's a hell of a lot of sand to search.