In December 1946 the New York Times credited James J. Kilroy, a welding inspector at the Bethlehem Steel shipyard in Quincy, Massachusetts, with starting the craze. Usually, inspectors used a small chalk mark, but welders were erasing those to get double-paid for their work. To prevent this, Mr Kilroy marked his welding work with the long crayoned phrase ("Kilroy was here") on the items he inspected. The graffito became a common sight around the shipyard and was imitated by workers when they were drafted and sent around the world. As the war progressed, people began opening void spaces on ships for repair, and the mysterious Mr Kilroy's name would be found there, in sealed compartments "where no one had been before."
A human like sub species, who prefers dark enclosed spaces. Usually has two feeble arms which it is unable to support fully, and often collapses in a fit of panic at the call of a siren. In popular slang, a kilroy is someone who shows no sense of self respect or makes no effort with their physical appearance.
Ted: What's that stain on your jeans man?
Damien: oops bbq sauce, I had it for dinner on Wednesday
TEd: Dame, you are the ultimate kilroy