They Know Their Groceries is a 1929 Vitaphone Varieties short comedy film directed by Bryan Foy.
It stars vaudeville comedy duo Flournoy Miller and Aubrey Lyles and features an African American cast.
The plot involves inattentive grocers.
A review of the film described it as funny but not hilarious.
You can help Wikipedia by expanding it.This article about a short silent comedy film is a stub.