What is Arse Sack?
1.
alternative for bum bag, a bag which one wears atop their buttocks, (secured by a belt-like device with a clip for attachment and detachment) while running, walking, etc.
in the television series, 'the nanny', yeta wears an 'arse sack' incorrectly, and wears it on the front, hence the name 'arse sack' or 'bum bag'
"hey, mum, have you got your arse sack on yet so we can get runnin'"