A couple years out of college, Cooper Barrett still doesn't have his dream job, he's possibly fallen for his across-the-hall neighbor, Kelly Bishop, and he can't seem to avoid major trouble, along with his roommates, Neal and Barry. Rounding out the gang is Cooper's older brother, Josh, who is constantly popping in to hang with the fellas and get some peace from his wife, Leslie, and their kids. Cooper struggles through the messy and hilarious disasters of life after college - a night in jail, crazy ex-girlfriends, going broke - giving us guidance so we can avoid the same mistakes.
After sales for their hangover cure are slower than expected, the guys decide to take part in a drug trial for quick cash, but their plans are unexpectedly derailed by Paul Abdul. Meanwhile, Kelly faces an awkward situation after spending time with Leslie and Josh.
When Kelly gets invited to her ex-boyfriend's wedding in Mexico, she doesn't want to show up alone - so she decides to bring Cooper as her plus one. But when getting to the wedding becomes a south-of-the-border logistical nightmare, Cooper enlists Neal, Barry, Josh and Leslie to come to their rescue.
Cooper faces the ultimate, life-halting devastation when he loses his phone, and the guys stop at nothing to help him get it back. Meanwhile, Leslie and Kelly's karaoke duet turns into an all-out bar brawl.
When Barry and his new girlfriend, Ashley, seem to be moving too fast, Cooper, Neal and Kelly try to intervene before he gets in too deep.
Meanwhile, Josh's attempt to outshine his co-worker leads him into dangerous territory.
When Kelly tells Cooper that the state of his apartment is ruining their chances at taking their relationship to the next level, he sets a meeting with their landlord, Virgil, in an attempt to fix things around the gang's place. But after their first meeting takes a turn for the worse, an epic battle between landlord and tenant ensues.
When Cameron, the gang's old friend from college, wants to crash at Cooper's apartment, everyone is excited to see him. But after he quickly wears out his welcome, the guys will try anything to get him out for good.
Cooper's ex-girlfriend resurfaces in a way that results in some serious public humiliation for him. Neal tries to intervene, but things quickly spiral out of control. Meanwhile, Kelly meets a new guy who shares her love of competition and Josh tries his hardest to keep Leslie out of group hangouts.
As Barry's Grandmother's Hangover Cure gains momentum in the marketplace, Cooper is getting all the credit, which leaves Barry and Neil frustrated. But when a rival CEO (guest star Victoria Justice) attempts to snatch the hangover cure crown away from them, the gang will have to band together to retain it.
When Cooper and Josh's parents come to visit, the boys try to be on their best behavior, but things change when their Dad reveals a secret leading to a crazy night and a run-in with rapper Juicy J. Meanwhile, Barry tries to help Neal overcome an unappealing addiction.
A potential buyer for Barry's Grandma's Hangover Cure turns out to be an old classmate of Cooper and Neal's, with whom Neal refuses to work, due to an issue from their past. Meanwhile, after a pipe bursts in her apartment, Kelly stays with Josh and Leslie and becomes obsessed with discovering what's behind a secret door in their home.
Cooper and Kelly try to make each other jealous by pretending to enjoy dating other people, while Neal and Barry end up dating a polyamorous girl together.
When the gang throws Cooper a surprise birthday party, things go south after Kelly witnesses Cooper and Ramona sharing a kiss.