- just for chagrins, lets just suppose that everything in this film is embellished (#)
- That might be neat to find out just for chagrins. (#)
- Will probably resurrect the F body and try the filter with it (just for chagrins..) (#)
etc. These from the single page of Google hits for this phrase. Not so many cites, but I was surprised that there were any at all.
I believe that per the technical definition, these aren't eggcorns; they're just plain ol' malapropisms. I suppose these cites essentially mean that some people don't know what chagrin means. That's not so surprising, I suppose; it's not a term that comes up in everyday speech.
So: probably not an evolutionary development. Just a little mutation.