Mike and Sulley are visiting Monsters University for the weekend to see how their Oozma Kappa fraternity brothers are doing. The group is throwing its first party, but no one has shown up. Fortunately, Mike and Sulley have a plan to liven up the house, to which using a borrowed door station, they sneak into a party at the Roar Omega Roar fraternity and steal all of its food and guests to fill the Oozma Kappa house. The supply runs take them through the closet doors of a married couple's bedroom, repeatedly disturbing their sleep.
Once they have the party fully stocked, Scott "Squishy" Squibbles' mother Sherri walks in on it while doing a load of laundry. She is angry with the fraternity, but only because they did not invite her. After lighting a bonfire on the lawn, Sherri introduces the crowd to "door jumping"/"door jamming", involving jumping from the roof with the help of two doors to land safely on the lawn. The guests congratulate the Oozma Kappas for throwing a great party, and many of them decide to pledge the fraternity.
In a post-credits scene, the husband and wife wake their son Timmy up and ask if they can sleep with him, saying that there are monsters in their closet. Timmy vehemently replies, "That's what I've been trying to tell you!".