Krippendorf's Tribe

Krippendorf's Tribe is a movie starring Richard Dreyfuss, Jenna Elfman, and Natasha Lyonne. An anthropologist creates a fictitious lost New Guinea tribe using his family members to cover-up for his mis-use of grant moneys.
After squandering his grant money, despondent and recently widowed anthropologist James Krippendorf must produce hard evidence of the existence of a heretofore undiscovered New Guinea tribe. Grass skirts, makeup, and staged rituals transform his three troubled children into the Shelmikedmu, a primitive culture whose habits enthrall scholars. But when a spiteful rival threatens to blow the whistle on Krippendorf's ruse, he gets into the act as well.