He realised what Sam was doing. It was probably the oldest trick in the hunter's book, of course. He almost sighed to himself, but knew it had to be done. Holy water or not, Dean was Dean. The anti-possession tattoo on his chest was enough to prove he wasn't possessed. Still, better humour little brother.
He took a sip and wanted to make a you spit in my beer gag, but refrained. 'Yeah? So somehow you've forgotten the past few weeks of your life here. Last I saw you, you pulled a demon out of some man's body.'