Via Web Curios, we quite enjoyed this well-researched history of one of the first proto-memes (see also here and here) of modern times in the graffito tag propagated by US and British service members during WWII, to mark the arrival of forward units in far-flung bases and for the soldiers to come, a phatic communion—anonymous and a gesture of camaraderie, in Kilroy was Here. 
The long-nosed figured peering over a fence, drawn on walls, equipment and any other bare surface also went by the other monickers—with strong resonance for contemporary meme culture—in Chad and the Goon, with the more nuanced UK-format captioned, according to context, with the snowclone, “Wot, no X?” as a way to complain about supply shortages at the front and rationing back home. Hitler and Stalin were supposedly convinced that Kilroy was some sort of codeword used by Allied intelligence. The lament over wartime austerity is considered one possible origin of the figure this side of the Atlantic, another being a shipyard inspector in Quincy Massachusetts, one James J Kilroy, who marked his seal of approval with the phrase in crayon on riveters’ work—yet another suggestion, the character might have started with a case of pareidolia in electricians over circuit schema—in any case, the versions merged, incorporating the different elements of the lore and was an early modern example of memetic forces, underpinned by repetition, variation and driven by the collective logistics of the war effort.
