The Attitude Factor (1981)
A school bus safety film about the attitudes of bus drivers focuses most of its story on a driver named Barbara Blackstone. It begins with Barbara, a lady with a positive attitude, winning an award for "best all-around driver"; by the end, she is worn down by the mother of a special needs child who constantly complains she's late. Barbara's meltdown to misery is a spectacle to behold and great material for riffing. The short is on YouTube.