Dave Hanson, I am another NATO veteran who first encountered mayonnaise on chips at a Schnell Imbiss. That's one of the few applications in which mayonnaise from a jar (preferably Hellman's in this part of the world) actually works better than the real, genuine, home-made article.
My husband and I both served in Germany, some ten years apart. Our private conversation was speckled with Soldatendeutsch -- stuck in a Stau on the way to the Schnell Imbiss kind of thing. The late 20th-century version of ex-Raj people whose shot of whisky was always a chota peg.