German Goitre Meaning

(US Midwest, idiomatic, humorous) A protruding stomach, especially one supposed to be indicative of excessive consumption of beer.

Example: 1939, American Flint, vol. 28, p. 41
  Brothers Gribble, Berger, Wolf, Shadwill and the writer are still nursing their “beer muscles.” I mean German goitres.
1956, "Advantages of Being Fat," Milwaukee Journal, 8 Oct., p. 22 (retrieved 3 Jan. 2010):
  Any man who likes playing Santa Claus is in much better shape come Christmas if he has a German goiter.