She's coming up 13 and has been calling me "Mum" for years; DS who's 7 also calls me Mum.
Recently she's started calling me "Mummy", not at home (very often) but in public and on Facebook.
She has a friend who does this, and with both of them it's usually "Thank you, Mummy" in a sickly-sweet voice whilst going all wide-eyed and "coy".
It makes my fucking teeth itch. Do I just let her get on with it and hope it passes or should I tell her I find it irritating and ask her not to do it?