Eager to have a younger sibling, a lonely kid (voiced by Anton Starkman) beseeches the storks to deliver a baby to his workaholic parents -- despite the fact that the birds have long since gotten out of the baby business, and now courier packages for an Internet merchant. But the discovery of an infant in the warehouse inventory forces the delivery service's recently promoted stork owner (Andy Samberg) to deliver one last bundle of joy.
Two years after feuding with a rowdy frat that moved next door to them, young parents Mac (Seth Rogen) and Kelly (Rose Byrne) are about to have their second child and move to a new house. Unfortunately, their attempts to sell their current home hit a snag when a sorority led by a rebellious college student (Chloë Grace Moretz) become their new neighbors. Desperate to get rid of the hard-partying gals, the couple forge an alliance with Teddy (Zac Efron), the former fratboy who tormented them the last time around.