After a few knocks, it was clear that no one was going to answer. We figured that maybe everyone was out on the balcony deck with DLR and they couldn't hear us. We decided to head up to the roof and see if we'd be able to get a vantage point of the party from there.
When Mike went upstairs to go to his apartment, he discovered that someone (who'd apparently spend the majority of the evening drinking red wine) had make a big purple mess right outside his door. When I apologized on behalf of the unknown guest, Mike shrugged and earned the Fonzie thumbs-up of Coolness by shrugging and replying "Who cares? This is why I own a mop!"