Did You Hear the One About the Traveling Saleslady? (1968)

Agatha Knabenshu arrives in a small town in Missouri to sell player pianos to the locals. She's fired after her disastrous sales attempts nearly destroy the town. The stranded saleslady becomes friendly with an equally bumbling inventor and moves in with his family. The two then try to sell his automatic milking machine, but things turn sour when their demonstration causes a stampede.