Buffy's blushing. It's pretty easy for Spike to guess what she's thinking about. He remembers those meetings pretty well himself. He doesn't blush, but he does look down for a moment.

When Casey speaks, he looks up sharply, then glances at Buffy. "No," he says quickly. "I don't have a girl." Is it really that obvious?

To Buffy, he asks, "You learned to mix anything yet? Wouldn't mind seeing what you've got."