Comedian Sal Howard has a big problem: his wife, scientist Dr. Dana Howard, doesn't want kids. To save his marriage, Sal tricks Dana into thinking he's become a real baby to show Dana the joys of motherhood. Sal's harebrained scheme works.
But the plan backfires when Dana develops a hormonal serum that can transform Sal into a full-time, adult baby - forever! Manbaby is an absurd, comic fairy tale about what it means to grow up.