Usually accompanied by a simple sketch of a bald-headed, long-nosed character peering over a wall, the graffito went viral before anyone knew the term.
Its origins are uncertain, but a popular legend centers around a Quincy-based ship inspector named James Kilroy, who would scrawl the message as his O.K. on hulls and tanks.
More significantly, the phrase is engraved in two hidden corners of the World War II Memorial in Washington, D.C., a warm wink to “the greatest generation” amid the grey granite.
Like all historic memorials, it’s an important one. Memorials honor those who sacrificed for a cause greater than themselves, and draw visitors out of themselves and into that cause.