Working the checkout at a supermarket is similar to being in a gym, with much of the day dedicated to making awkward small talk while lifting items.
Our grocery-packing insider says the bagging of items is often the most frustrating part of the job, especially when people unpack and rearrange items after they have been packed.
"It shows you are a prissy idiot who doesn't trust how we have done it and makes us want to pack it even worse in the future."
On that note, she says people who provide their own bags really should find another way to save the environment (unless they are special supermarket environment bags).
"They bring all sorts of bags and they usually have oddly-shaped material and won't fit on our bag holders, so the contents go everywhere, or we have to hold the strap with one hand and pack with the other."
Some customers even bring in reused plastic bags that look like they are 5 years old and are covered in holes and mould.
Smiling and greeting your operator is a small gesture much appreciated.
"It's like people who don't smile think we are the scum of the earth. We're only doing our job - and greeting people is the main part."
She says when customers don't reciprocate a greeting the rest of the packing-journey is usually more awkward.
"We are forced to be cheerful and make conversation - so waiting for a trolley full of groceries to be scanned and put in plastic bags while being completely silent can be very uncomfortable."