"Clap my hands and jump for joy; I was here before Kilroy" - "Sorry to spoil your little joke; I was here, but my pencil broke."".
The origin of Kilroy graffiti is speculative but Kilroy Was Here doodles appear in many cultures but is mostly associated with World War II and through the Korean War.
WWII and Korean War United States servicemen would draw the doodle and the text "Kilroy Was Here" pretty much on any surface where they were stationed.
There are many urban legends and folk tales surrounding Kilroy graffiti including one where Adolf Hitler believed that Kilroy was an American super spy.
The Alien Kilroys here are my hand-drawn collection that I used as my own e-mail graffiti at the office.
More Kilroys to come.....