Reference:
There is a famous scouse folk song (don't know what it's called) that has the lines - "We speak with an accent exceedingly rare,Stand under a statue exceedingly bare,If you want a cathedral we've got one to spare,In our Liverpool home."And the scousers used to sometimes sing this at matches in the 70's.This was then updated by opposing football fans and given new words which were -"You look in a dustbin for something to eat,You find a dead cat and you think it's a treat,In your Liverpool slums,in your Liverpool slums."Hence -looking in a "dustbin" for something to eat = bindippers.
Ah thank you, rather along the lines of us referring to a local team as a family from Emmerdale then. And of course the team I mention, their supporters referring to us as a supermarket.