The Yiddish–Dutch–German “Smallpox” Exchange

Tom Klein writes:

I wonder if you can shed light on the following. I have heard elderly couples remark, when reminiscing about the trials and tribulations they have gone through in their lives, “Mir hobn gepokt un gemozelt.” Although I understand the intent of the phrase, its exact meaning and origins elude me. Can you help?

A literal translation of the Yiddish expression that Mr. Klein asks about is “We’ve been smallpoxed and measled” or “We’ve had smallpox and measles.” In ordinary English one would say, “We’ve been through it all.”