That was pure awesome. I actually lol'd at the mass exodus from the dinner table. As pretty much everyone has said, crotchety relatives hidden snapes is love, as is tipsy Severus and clueless Harry.
It occurs to me now that one of the nice qualities of Harry is that he's frequently in situations where plot moves FAST and he's desperately trying to keep up. This is difficult to do in Snarry because Snape's world seems so much more deliberate and thoughtful. But you've just made something wonderful: Snapes that move at the speed of Weasleys. Excellent. It brings out something I really like in Harry.