Ken, Paul, and Harry enter Pete's office to find him proudly brandishing a shotgun (although it could be a BB gun for all I know) over his head. "Same price as a chip and dip." Too bad there's nothing left over for therapy. He points it at all of them in turn, and then heads to his door and starts aiming at various women. I don't know if the concept of hazard pay had been invented yet, but if not, I think this was the seminal moment. He keeps it up until Hildy calmly pushes the thing down and informs him that his 4:30 is waiting. The boys file out, and Hildy takes the gun and watches them go with a "boys will be morons" look. I'm starting to like her.
So it's a Nixon brainstorming meeting, and present are Don, Bertram, Roger, Harry, and Pete. After some discussion about whether Kennedy will in fact be Nixon's opponent, Roger expresses skepticism of Kennedy's appeal. Basically, Pete is the only one with a true sense of Kennedy's potential popularity, even comparing him to Elvis, but he expresses that opinion in such a typically smarmy and smug way that I can't say I'm unhappy when he gets dismissively shot down by both Bertram and Roger. However, when Roger asks if they can hear from the adults, Don seems a little taken aback by Roger's imperiousness. It's almost like he's got some reason to see him in a new light! Seriously, though, it does seem like Don is wondering if he's more in Pete's position in the company than in Roger's, which makes his later actions make even more sense.
Betty is just putting the finishing touches on a lovely-looking roast beef as Don comes home, and she tells him what she's made. Don: "You know it's just me tonight, right?" Let me guess: Still mad? The two of them regard each other for a long moment, and then Don heads out of the room. I love Jon Hamm, and this character is interesting, but all that said: What a douche.
Pete is sitting in a chair, impassively cradling the gun in his lap, as his wife somewhat hysterically berates him for returning the chip and dip; the obvious implication is that it was not, in fact, an extra, and Pete did this without his wife's knowledge. Pete regards his wife with loathing through her diatribe, and I really hope he didn't have enough store credit left over for ammunition.
At the office, presumably the next day, Don, waiting for the elevator, sees it open to spit out Pete, sheepishly carrying the gun. He heads away without a word, but the hilarious thing is the "WTF?" look the elevator attendant gives him. That's how you make the most of a non-speaking scene. Don then conspiratorially asks the attendant, "Hollis," for a word, and pulls out some bills as the door closes.