<P> Deanna tries to make amends with Maddie, but she tells her that she is leaving college since she has no means of completing the rest of the year on her own . The girls then come up with a plan to throw a party to raise money to pay for Deanna's tuition . Since everyone is at Christina Aguilera concert, Helen posts the message on her Twitter, claiming Aguilera will be at the party after her show . Christine shows up with her husband, as do Mike and Sandy . Mike offers to give Deanna a 401K check to pay her tuition, but Deanna refuses to take it . The party is not a success until Aguilera (who ends up being Leonor's cousin) arrives and she puts on a show with Deanna and the girls to an excited crowd . </P> <P> Later on, Deanna is due to repeat her presentation in class . She is still nervous until Maddie, Helen, Amanda, Debbie, and all the sorority sisters show up to support her, and Deanna manages to give the presentation with ease . At the end of the year, Deanna and Maddie graduate together, with all their friends and family there to support them . Maddie encourages Deanna to throw her cap in the air . She does so, and it hits Dan in the face, knocking out an earring he was wearing while Marcie berates him for losing the expensive diamond stud . </P> <Ul> <Li> Melissa McCarthy as Deanna "Dee Rock" Miles (née Cook) </Li> <Li> Molly Gordon as Maddie Miles, Dan and Deanna's daughter </Li> <Li> Gillian Jacobs as Helen, a sorority sister who is older than the rest due to having been in a coma for eight years . </Li> <Li> Maya Rudolph as Christine Davenport, Deanna's neurotic and heavy drinking best friend </Li> <Li> Jessie Ennis as Debbie, a sorority sister with "issues" </Li> <Li> Adria Arjona as Amanda, another sorority sister with "issues" </Li> <Li> Matt Walsh as Daniel "Dan" Miles, Deanna's ex-husband, Maddie's father </Li> <Li> Julie Bowen as Marcie Strong, a real estate agent, Deanna's nemesis and Dan's lover </Li> <Li> Debby Ryan as Jennifer, a "mean girl" in Deanna's archaeology class </Li> <Li> Stephen Root as Michael "Mike" Cook, Deanna's father and Maddie's grandfather </Li> <Li> Jacki Weaver as Sandy Cook, Deanna's mother and Maddie's grandmother </Li> <Li> Luke Benward as Jack Strong, a frat boy infatuated with Deanna </Li> <Li> Jimmy O. Yang as Tyler, Maddie's boyfriend and Jack's friend </Li> <Li> Chris Parnell as Wayne Truzack, Deanna's professor </Li> <Li> Heidi Gardner as Leonor, Deanna's reclusive Goth roommate </Li> <Li> Yani Smone as Trina, Jennifer's snarky sidekick </Li> <Li> Damon Jones as Frank Davenport, Christine's husband </Li> <Li> Ben Falcone as Dale, the Uber driver </Li> <Li> Nat Faxon as Lance </Li> <Li> Sarah Baker as Gildred </Li> <Li> Karen Maruyama as Mediator </Li> <Li> Steve Mallory as Bill </Li> <Li> Courtney Patterson as Amy </Li> <Li> Steve Falcone (Ben Falcone's real - life father) as Older Man #1 / Vince </Li> <Li> Michael D. McCarthy (Melissa McCarthy's real - life father) as Older Man #2 / Dennis </Li> <Li> Christina Aguilera as herself (cameo) </Li> </Ul> <Li> Melissa McCarthy as Deanna "Dee Rock" Miles (née Cook) </Li>

Who is jack in life of the party