That cartoon face with that phrase would appear spray-painted on walls, scrawled in lockers and written on the back of high school notebooks for decades. What is it supposed to be? What does it mean? Who knows. The meme started with soldiers deployed around the world before World War II and rippled out from there.
The best guess about the origin of the Kilroy image is that two already popular memes merged together in an unholy alliance -- the dude with the nose was probably a well-known British doodle called "Mr. Chad," and as for the caption, we can thank an American welding inspector from Quincy, Mass., named James J. Kilroy.
Via Jason Taellious
What a legacy.
Back in those days, it was up to men like Kilroy to inspect the rivets of whatever piece of metal their employers paid them to stare at all day. Most inspectors simply approved the work by marking it with a piece of chalk, but Kilroy decided to add some excitement to his dead-end job by signing "Kilroy was here." Apparently he was pretty goddamn prolific.
Here he is on the Berlin Wall.