Upstairs, when Angela and Meredith come into the office to a cry of "Surprise!", Meredith assumes it's for Angela and turns to her to weakly say, "Surprise." Angela explains the confusion. This is going to be a great party.
Warehouse. Jim asks if he should stay with the box. No, no! He must go upstairs to the party! Well, okay. Dwight THs that he doesn't entirely trust Jim, but he doesn't have a choice. Jim gleefully and thoroughly tapes Dwight into the box with one of those big tape-rolling guns. Zzzzzzzzip! Zzzzzzzzip! Zzzzzzzzzip!
With the party in full swing, Michael scarfs ice-cream cake while forcing Meredith to admit that encountering her birthday party a month early certainly was a surprise, all right. Michael manages to mock her and her lactose intolerance, so I'm thinking it's probably her best party ever.
Warehouse. Dwight's box. Eyeholes.
At reception, Pam kind of can't believe Dwight's really down in the warehouse in a box. Jim encourages her to go down there and "work [her] magic," so Pam, still in her party hat, makes her way to the warehouse, where she makes a great show of getting on her cell phone and loudly talking strategy talk designed to make Dwight crazy, which it apparently does, since he's so much with the excited wiggling that the box falls over with a thud.
At the party, Jim congratulates Michael on the generous gift to Oscar's charity, and this is how Michael learns that he has pledged twenty-five dollars a mile for a walkathon, not twenty-five dollars total. So Michael awkwardly calls Oscar into his office to retract the pledge. Oscar kind of gives him shit about it, which I have to say I don't really agree with -- if the person clearly didn't understand what they were doing when they pledged a sort of outlier amount, I don't really agree with holding them to it on a technicality, even though Michael is the dick here just like he is in almost every other situation. Michael winds up asking Oscar how many miles his nephew walked last year. When he hears that the answer is "eighteen," Michael mutters, "Son of a bitch...that is impressive, good for him."
Dwight cuts the box open from the inside. Good thing he carries a blade! He then proceeds to climb out of it, emerging like a bird from an egg. But a crazy, angry bird. A crazy, angry bird with a list of enemies. Props to Rainn Wilson for that stunt, and extra props to whomever decided that Darryl, in his first significant appearance, should be standing there watching when Dwight turns around. I bet that's the first time in a while that a guy's come out of one of the boxes on the warehouse floor.