As a child, Lainy plays a mom giving birth, with her best friend Kate. After they grow up, both are teachers at the same school. Kate is married and becomes pregnant. When Dave, Lainy’s boyfriend of four years, invites her to dinner and asks her to participate in a threesome, she loses her cool as she was expecting a proposal. In her class the next day, she burns her students’ books and sets off the fire alarm.

Lainy learns about Kate’s pregnancy when they meet up for lunch. Next day at school, Lainy learns that another younger teacher Shirley is also pregnant.

Lainy and Kate go to a maternity clothing store, where she puts on a fake pregnancy belly. She is happy with people on the street wishing her well and treating her with respect. She dons the fake belly and visits a Prenatal Yoga class called “Mamaste”, where she befriends Megan, a pregnant woman.

Megan invites Lainy to her home for dinner, where she meets her brother Josh and husband Steve. Her belly accidentally catches fire and while patching it up, she talks to Megan for a while, who thanks Lainy for giving her strength, so Lainy continues faking her pregnancy.

Lainy’s co-worker, Fallon, is aware of her faking her pregnancy and tells her to stop, but Lainy does not listen. At a children’s store, Megan’s son sees Lainy and Kate and observes the lack of baby belly. Steve and Megan are also there, but Lainy hides so they cannot see her.

Josh calls Lainy for a date on an ice skating rink and then on a City Cruises Yacht dinner and dance. They bump into Dave, her ex-boyfriend, who believes her when says she got pregnant during a Thanksgiving Black Friday sale.

Megan visits Lainy at her school, inviting her to join her at a therapeutic class for pregnant women. Lainy grabs a helium balloon and puts it beneath her dress to make it appear as if she is pregnant. Fallon also shows up at the class, pretending to be pregnant.

When visiting Megan to babysit her son, Lainy kisses Josh and goes to the garage. Before they have sex, she covers Josh with an eye mask and keeps her shirt on to keep her fake pregnancy from being discovered. They have sex in the cowgirl position, during which the garage door opens by mistake. After Josh admits he feels he can really trust her and believes they could make it together with the baby, she then abruptly leaves, saying she cannot continue with him.

Lainy confides to Fallon about getting rid of her (non-existent) baby and is overheard by Shirley who tells Kate about it. Kate invites Lainy to her baby shower, where Megan, her husband and Josh arrive upon Shirley’s invitation. Lainy places a roast chicken up her dress to keep up the fake pregnancy, but when confronted about it, drops the chicken and tells everyone she is not really pregnant, whereupon the upset Megan and Josh leave.

Kate and Megan both reconcile with Lainy. She finally tells Josh she loves him and her real name. Dave visits Lainy, who first lies to him saying he is going to be the father of triplets and then watches his relief when she removes her fake pregnant cushion.

Lainy goes back to teaching, when one of her students tells her there is a Zamboni outside. They all go out to meet Josh, who confesses his love for her. They ride the Zamboni, causing a lot of accidental property damage on the way out of the school.