while browseing google images for (ultrasonic) scent diffusers this picture of a fridge deodorizer was included, one of the anomalies that never fail to make image searches interesting.
the coffea scent diffuser, a small shallow cup with a lid perforated with many holes, filled with coffea grounds and hung in a fridge from one of the wire shelves by the hook on top of the diffuser. it may clear the fridge of odours or cover them up with cold coffea odour.