The phrase "Foo was here" was used from 1941–45 as the Australian equivalent of "Kilroy was here". "Foo" was thought of as a gremlin by the Royal Australian Air Force, and the name may have been derived from the 1930s cartoon Smokey Stover in which the character used the word "foo" when he could not remember the name of something.[12] It has been claimed that Foo came from the acronym for Forward Observation Officer, but this is unlikely.[13]