Today in 1942, US Patent 2280336 A was issued, an invention of Herman J. Maihack, for his “Protector For Beer Can Openers.” There’s no Abstract, although in the description it includes this summary:

This invention relates to protectors for beer can openers, and the like, andy has for one of its objects the production of a. simple and efficient means in the nature of a hood or cap which is adapted to be carried by a piercing can opener so as to overhang the pierced opening within the top of a can and prevent the spray of beer or other liquid outwardly through the opening which is being cut in the top of the can.

A further object of this invention is the production of a simple and efficient means for attaching the protector to the well-known type of piercing opener.