Green’s Dictionary of Slang

1. (US) a derog. name for a German.

1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant.
1915		J.P. Poe Jr letter 24 July in Morse The Vanguard of American Volunteers (1918) 80: Of course we are going to win; but the ‘Limburgers’ are putting up a great fight.
1983		Maledicta VII 25: Germans, for a while after 1904, were called limburger,sometimes spelled and pronounced limberger, which was shortened to limberg.

2. (US campus) an unpopular or unattractive young woman.

1984

Eble Campus Sl. Sept. 5: limburger – a girl no one else would date: Tim goes out with such a limburger.