Pam "runs into" Angela, buying a Baby Ruth from the vending machine in the break room, and asks whether she's bringing anyone to Jim's party, date-wise. Angela coolly says that she isn't, and Pam lets it go. She's about to get something from the machine herself, but Angela's not done shopping; she gets another Baby Ruth with a cold "excuse me" at Pam's temerity in trying to cut ahead of her. Pam gives us a conspiratorial grin, and Angela gives Pam a dirty look. Dirtier than usual, that is.
This has given Michael enough time to spin himself a self-serving reason for his exclusion from Jim's party. He THs about the natural distance between a boss and his employees, over B-roll footage of him annoying everyone in the office with a boxing kitten puppet. But this doesn't mean he's going to let it go, especially if there's a party invitation in it for him. He decides he needs to be "approachabler."
So Michael takes his cup o'noodles and joins a rather surprised Jim, Pam, Kevin, and Oscar at the break room table. Michael talks about how noodles reminds him of college, and how he misses the parties. Jim cuts an "oh, shit" look at the camera as Michael anvils about how the professors would come too. "They were the most fun," he claims. Michael doesn't have agendas this clear for his actual staff meetings.
Jim THs that he has imported beer, and a karaoke machine, and didn't invite Michael. "Three ingredients for a great party," he says. He explains that he wants everyone to be able to relax, and that he invited everyone from the office because his roommate wants to meet everyone. Everyone? Really? Even...? "He thinks I'm making Dwight up," Jim says of his roommate, and shudders, "He is very real."
The camera dashes naughtily up to Reception and ducks down, focused on Pam's face. "What?" she says. The camera swings around to Dwight, making out with his Baby Ruth, and then swings back to Pam. "Yes! Thank you!" she says. It's like she's thanking me. Which almost makes up for having to watch Dwight eat his candy bar inside the wrapper like he's performing cunnilingus on it.
Later, Dwight starts to ask Jim about which of the internet's "several options" to get to his place would be best, and Jim hurriedly shushes Dwight because Michael's up at Reception right now, and that much proximity will stretch even the TV cone of silence to the limit. Trying to stay discreet, Jim whispers to Dwight that Michael doesn't know about it. And he realizes that the only way to keep it that way is to tell Dwight it's a surprise party for Michael. Which is what he does.