Little things amuse little minds

[Caken]

My grandma always used to say this and I understand the meaning of that and what she was alluding to with me , but what does the other part, ‘little trousers fit little behinds’ mean?

I realise I’m probably missing the glaringly obvious!

Likewise does anyone else have any seemingly commonplace phrases they just don’t get?

I've not heard the little trousers one so can't help you there.

I never really understood "you'll be laughing the other side of your face"

Also the one that goes something like "you're not so green as you are cabbage looking".

And " lucky white heather" when someone has bad luck.

Bumping for you

I always took it just as part of the fun rhyme. It’s a fact, little trousers fit little behinds and therefore it’s a fact that little things please little minds. My Nan always said this.