U.S. Patent 6,834,453 is for a piece of foam in the shape of an “M” worn on the head.
The invention, cleverly and appropriately named the “Head Mounted Letter ‘M’ Display,” is designed for sports fans who want to support their teams that begin with the letter “M.”
The funniest aspect of this patent (other than that one can get a patent for a head-mounted letter of the alphabet) is all the complex diagrams of a guy wearing an “M” on his head.
— U.S. Patent 6,834,453 , Dec. 28, 2004.