Afterwards, Holly comes up to congratulate Michael on his performance, because she doesn't yet know about how he does this at every opportunity until everyone wants to kill themselves. Kevin calls Michael on his cell, summoning him to the grocery store. "It's a big day for him," Holly says, which Michael blandly agrees with before heading off. They share another dorky-humor moment before Michael walks to his car.
When Michael gets to the grocery store, Kevin's rolling a shopping cart out next to none other than Jan. Michael isn't exactly thrilled to see her, especially as a reason for being called away from the party, but Kevin knowingly tells him, "I think you kids have a lot to catch up on." And when Kevin rolls his cart away, it reveals something about Jan that the show has been hiding about Angela since the strike ended. You guessed it -- JAN IS PREGNANT. Sorry about the all caps there, but when my jaw dropped it landed on the shift key.
Back from the ads, Michael and Jan are sitting at an outdoor table and talking. Michael is all excited and solicitous about the baby that he naturally thinks is his, until Jan has to admit that he's not the father. She insists she didn't cheat on him; she went to a sperm bank. "I need to make this one count," she THs after breaking the news to him. As they say goodbye, Jan invites him to her Lamaze class the next day, but he demurs. Afterwards, he THs that he always knew two things: he loves sex, and he wants to have kids. Which he thought was a decent combo, but now he's thinking it might have to be one or the other. Yes, a lot of parents discover that for the first year or so as well.
Back at the party, it's gotten dark and the fireworks have begun. Pam and Jim snuggle in lawn chairs. Dwight and Kevin applaud together. Phyllis and Bob Vance from Vance Refrigeration kiss. Poor, single Toby just shrugs at us over his beer bottle. Angela warns Phyllis that this is the last party she'll ever plan. Is this feud going to pay off, ever? Jim eases that ring box out of his jacket pocket, and says to Pam, "Hey." And suddenly Andy makes his first appearance of the episode, hijacking the microphone and stopping the band. Oh, by the way, his parents are here. He's got something to say to Angela, and won't be discouraged by her head-shaking scowls. Which, I guess if he ever was discouraged by that, their relationship wouldn't have lasted this long anyway. He leaves the stage, pulling Darryl's synth off its stand. Yeah, Andy's proposing to Angela. And her answer? "Okay," she whispers. "And the crowd goes wild!" Andy celebrates, to a smattering of applause. Dwight, naturally, is devastated. Jim eases that ring box right back into his pocket. That'll learn Pam to shoot her mouth off to the cameras about perfect timing.