I do not have my 'mum head' on!
I deal with a particular Barrister at work almost daily (I instruct him a lot for Counsel) and he's fantastic at his job, really very good at what he does and a powerhouse in his area of law.
However, at least once every other day when something changes regarding a case or a client, meaning my instructions for him change, he'll insinuate that I forgot to tell him because I had my 'mum head' on at the time!
Aarrrghhhh! And I get it, it's nothing major and there is a lot worse going on out there but every time he says it, I just want to respond with 'aah, yes that's right, just as you've got your knobhead on....'