During WWII, American servicemen began spreading this doodle with the words "Kilroy was here" all across Europe and Japan.
This tag became extremely popular and soldiers did their duty to draw it everywhere they went.
In 1946, in an effort to find the real Kilroy, the American Transit Association determined that this drawing originated with James Kilroy from Massachusetts.
James worked in a shipyard during the war and, according to the legend, was in charge of counting rivets.
James carried with him a piece of chalk to help him keep a proper count.
He began to mark the ship with "Kilroy was here" to prevent the other workers from erasing his chalk marks.
After a while he added the little doodle and thus an icon was born.
When the ships were completed they were immediately filled with soldiers and sent overseas.
So...one of the first things the soldiers saw when they left the mainland was this image.