Behind the ears

Could you rephrase the expression “wash behind the ears?” Does it mean “try to listen more carefully?”

Washing behind the ears is something that children like to overlook, like brushing their teeth or washing their hands before a meal. So a parent might remind a child to remember to wash behind her ears.

Instead of saying ‘pay attention, please’, I could say “and now prick up your ears, please”, but that would be very colloquial.

Thank you, SanneT.
Instead of saying ‘pay attention, please’, we could say ‘clean the ear canals, please’ in Japanese, but that would be very colloquial and rude.

There´s an English equivalent, ie “clean your lugholes!”, which is also quite colloquial.

mimi no ana wo hojikutte yoku kike.
Try to listen more carefully after cleaning your lugholes!

Of course, ladies are not supposed to use this expression.

I shall avoid it like the plague!