The flag of the Republic of Central Lithuania, a short-lived state in Central Europe. It combines both the Coat of Arms of Poland and the Coat of Arms of Lithuania
self-made, basing on PD File:Coat of arms of Lithuania.svg and File:Coat of arms of Poland2 1919-1927.svg. Note that the image is a recreation of the flag rather than a rendering of any particular image.
Halibutt