"It'll come in handy!"

Because that old piece of cheese at the back of your fridge is going to come in handy for that fondue party you've not planned, right?!
A bit like the shellsuits at the back of your wardrobe…and no, they're never going to come back in! 

You're probably the sort who likes to be prepared for anything, and hoarding junk helps you cater for any eventuality...though it does mean your house is cluttered with stuff that's 99% useless.