David Cohen (Brandon Polansky) is a mildly autistic man ordered by a judge to attend an autism support group for six weeks after an incident in which he told pig jokes to a cop. While there, he meets Sarah Silverstein (Samantha Elisofon), a woman with non-verbal learning disability who helps run the group's drama club. At first she grates on him, but soon the two start to fall in love. But David's desire to appear normal threatens to tear them apart.
Keep the Change contains examples of:
- Amusement Park: The protagonists go to one. Sarah wants to go on the most intense rides, while David tries to talk her into something gentler. Even the merry-go-round turns out to be enough to make David queasy.
- Basement-Dweller: David still lives with his parents.
- Buses Are for Freaks: David is reluctant to take the bus because the homeless people creep him out. When he finally boards the bus towards the end to talk to Sarah, it's a sign that his hatred of weirdness is weakening.
- Celeb Crush: Sammy (Nicky Gottlieb), who runs the drama club with Sarah, is in love with David's cousin Matt Cone (Johnny Tchaikovsky), an actor who is Famed In-Story. When the group is asked what superpowers they wish they could have, Sammy's is the ability to make Matt Cone fall in love with him.
- Celebrity Resemblance: Angie, one of David's failed girlfriends, tells him he looks like Bono.
- Character Tics: David loudly snorts and groans when he's upset. He tells people it's allergies.
- Commonality Connection: After spending most of the movie trying to distance himself and Sarah from the "weirdos" in the support group, David realizes that he loves Sarah because she's weird, like him.
- Dating Service Disaster: David has had a string of internet girlfriends who all found him so off-putting in person that they dumped him after one date.
- Dude, Not Funny!: After telling a joke about pigs right to a cop's face, David is ordered by the court to enroll in a support group.
- Gold Digger: David's parents worry that Sarah is one and try to forbid him from seeing her. He doesn't listen.
- Pun: David is fond of these.
- Sensory Overload: One of the members of the support group wonders if this is the reason David seems so withdrawn. It isn't, he just doesn't want to be there.
- Title Drop: David doesn't know how to count change, so he pays people in large bills and says, "Keep the change."
- Womanchild: Sarah likes to sing songs meant for little kids.
