OK. How about this one? I am just about to welcome into my extended family a Francis. When I mentioned this to my friend she fell about laughing and said "you can't call him that!" Because, being a Northerner, I say "Fran-cis" and she, being a pansy Southerner, says "Frarn-cis". He is from the South too but now lives oop North.
I now can't call him anything and have to just look at him and try to catch his eye when I want to speak to him. My parents and brother call him Fran-cis without batting an eyelid.
I can't say Frarn-cis as I feel silly - but df says this is his given name and I am actually mispronouncing it if I say it my way.