Back in 2006, we here at LH (always ahead of the curve) discussed the WWI-era Tommyfied French “san fairy Ann” (ça ne fait rien); now Mark Liberman has posted about it at the Log, spurred by David Shariatmadari’s “That eggcorn moment” (“If you’ve been signalled out by friends for saying ‘when all is set and done’, you’re not alone – linguists even have a word for it”). Both Liberman and Shariatmadari quote a wonderful paragraph by Jeanette Winterson about “damp squid”; Liberman goes on to cite this further passage:
My father was in Ipres, (pronounced Wipers), during the War, and like many of his generation, came back with bits of French.
Ce ne fait rien turned into San Fairy Ann, meaning Stuff You, and then a new character emerged in Lancashire-speak, known as Fairy Ann; a got-up creature, no better than she should be, who couldn’t give a damn. ‘San Fairy Ann to you’, morphed into, ‘Who does she think she is? Fairy Ann?’
And he quotes he OED on san fairy ann., n.:
Jocular form repr. French ça ne fait rien ‘it does not matter’, said to have originated in army use in the war of 1914–18.
An expression of indifference to, or resigned acceptance of, a state of affairs. Also ellipt. as Fairy Ann.
And yes, I’m quite sure “signalled out” in the subhead is a deliberate eggcorn. (Thanks for the link, Eric!)