This was a movie short at the pictures before a main feature in the late 70s or early 80s I think?

A guys head in a shoe box. He has a beard. He Kept saying dont put the lid back on everytime the box was opened. A Confused man found the box in the garage on a sunny day. Everytime he took lid off the shoe box the man’s head in the box kept saying dont put the lid back on. The finder finally loses it and The final scene was the frustrated finder now spooked and scared throwing the box from a bridge to a garabage truck. Final shot is lid came off the box. The exposed head in the Box is in a big pile of garbage screaming for help. Camera zooms back and small shoe box with head in it blends in to the massive pile of garbage with mans head screaming, I have been trying to find out what this is for over twenty years,

Good luck guys,  and thank you in advance