When people leave their trolleys in the middle of the aisle while browsing the shelf halfway down the aisle so you have to move their trolley to get past.
Or when people have their trolley pushed to one side of the aisle but are looking for something on the other side, subsequently blocking the entire aisle.
When the checkout chick takes great interest in your shopping and comments on them. This has happened when buying pregnancy tests and condoms. No complete stranger I do not want to enter a conversation with you about my sex life or how I might be pregnant with my first child. For this reason I will mostly use the self service checkout unless I've done a full shop and have to go through the proper checkout. Then I will choose the one with the young teenage boy who will be too embarrassed while scanning pregnancy tests and condoms to start a conversation about them.
When people are oblivious to what their children are doing while in the supermarket. ie running up the aisles pushing the trolley that they're too short to see over the top of while mum and/or dad are deep in discussion for 10 mins over which brand of tomato sauce to buy, meanwhile their kids are ramming the trolley into shelves/display stands/other people etc
People who are talking loudly on their mobile phone. I followed a bloke around Coles the other day (not by choice mind you) and you could hear ever word he was saying from halfway up the aisle. Dude, I just want to shop in relative peace.
People who are on their phones going through the checkout totally ignoring the checkout chick. HANG UP YOUR PHONE! I'm not one for deep conversation with the checkout chick, but I do have manners.
People who take a full trolley through the self serve checkout. Now I love self serve and will go through with one of those half trolleys, but it's usually because I've got something heavy or I've done shopping elsewhere and can't manage a basket plus all my other bags. I'm usually done within a min or 2 and I will always go to a checkout that's in the end so my trolley isn't in the middle of walkway. I will admit through, I have done this once. But the queues for the proper checkouts were ridiculous and there was hardly anyone in the self serve section. It meant I was done well before I would've even been able to load my groceries on the conveyor belt.
People who can't work out self serve checkouts and take twice as long as what it would take to go through a normal checkout. I mean, they're really easy. If I accidentally double scan something I'll clear the item then call out to the attendant. If you wait for them to see your flashing light you'll wait forever so I just call out to them. I've never had an issue with anyone being rude and huffy about it, I mean that's why they're there - to help. But if I have to wait 10 mins for someone to scan through a loaf of bread, milk and some bananas, I get impatient very quickly!
People who go through full service checkouts with a handful of things while self service/express/baskets only checkouts are virtually empty.
The fact that on really busy times (ie Christmas) the supermarket still will only have 2-3 full checkouts operating despite there being 6-7 people queued up at each register with a full trolley piled with food. OPEN MORE REGISTERS! If I'm shopping in a crowd I'm already going to be grouchy. Waiting 45 min at the register will only make me ragey.
When you're standing in a line with only a few items and someone asks to go in front of you because they only have bread and milk. I usually say yes because it's easier, but why should they butt in just because they have 2 items to my 6? I get it when I have a full shop in my trolley and they're just buying milk or whatever, but some people think they're entitled. If it's someone with a screaming child or whatever I'll take pity and let them through no dramas because I can only guess that they want to get out of there faster than anyone else wants them to.
Wow, I just realised what a grouchy shopper I can be lol