Nathan writes 'Dearest Alice, I shall kill you last' on a birthday card, which is about the nicest thing he can say without wrecking his reputation as a Jerk Ass. Turns into a Dethroning Moment of Suck for Nathan, because they get together briefly, but she ditches him for another guy almost immediately.
Also leads to a Crowning Moment of Funny, when the Running Gag of Nathan giving out Ari's phone number instead of his own leads to all of Alice's communication going to Ari instead.
Nathan also reveals that he knows about it by sending her a text saying: 'just a heads up, I think I'm coming down with flu. I warned Daniel as well.', which is another Crowning Moment of Funny
Brad's twenty-first birthday party is, predictably, full of 'aww' moments.