Telephone camouflaged as a sandwich.
The only color available is basic black but it comes in a variety of sandwich fillings: American cheese, egg salad, peanut butter and an imported liverwurst.
Devised by Professor Carlson [Episode #52: "Smart Fit the Battle of Jericho"].
The term "Sandwich Phone" is also applied to a later device more accurately described as a "Sandwich and Potato Chip Phone" [Episode #89: "Closely Watched Planes"].