How to remove stuck cups

In a recent issue of my Magnet newsletter, I asked readers to help me separate two coffee cups that somehow got stuck together. (It’s the second-to-last item in the newsletter.) Almost all of the hundreds of suggestions I received involved cooling the small cup and heating the big one to allow thermal expansion to do its work, but that didn’t help. Can Recomendo readers come up with a solution? Send email to: markfrauenfelder+stuckcups@gmail.com — MF