For those hoping to make a killing on this “rare” beer can variant, keep this in mind...
https://en.wikipedia.org/wiki/Dag_Hammarskj%C3%B6ld_invert
A sheet of stamps with one color inverted slipped out, and once discovered, the USPS issued a huge number of stamps deliberately misprinted with the same error. The “rare” stamp is basically worthless now.
Dag Hammarskjold? Wasn’t he the Secretary general of the N.U.?