Kil‧roy /ˈkɪlrɔɪ/
an unknown or imaginary man, whose name is used in phrases such as ‘Kilroy was here’ or ‘Kilroy slept here’, which people often write on walls in public places. These phrases were first used by US soldiers in World War II, but their origin is not known.

[TahlilGaran] Dictionary of Contemporary English ▲