In the episode "Sergeant Gork" where Fred reminisce about his tall tales of adventure in world war 2, there is scene where Ester as a cafe singer in Germany lip sing a WWII tune titled Lili Marleen.

The tune sung by Marlene Dietrich is very catchy song and was a big hit with allied forces. I have never heard that song before hearing on Sanford and sometimes I catch myself singing verses from that song.

A memorable tune:

https://www.youtube.com/watch?v=gBi5j7yPwd0