I work in a large Australian grocery store as just a team member, one day when I was working in the self-checkouts, helping when people double scan, making sure people don't just not scan certain items, sometimes check bags, etc; this one guy we'll call RM for rude man, comes with half a trolley of items on a Saturday night half an hour before we close (it was 9.30). We were understand as 2 people called in sick so there was 3 of us, one as the tobacco counter where she can sell tobacco or serve people physically who don't want to do it themselves and some who come up and say 'you're welcome for saving your job'. Anyway RM turns to me and says
RM: Just a piece of advice I want you to pass onto your manager, many of us don't like using the self checkout and want some else to do it.
Me: Yeah all good I understand Sir, I'm very sorry about that although if you'd like you can use the register next to the tobacco shop and someone can put you through
RM: I don't like using that one either you should have a full lane register open at all times
Me: Usually at 9.30 it's not very busy as the people who do come through have a small amount of stuff so instead they come through self checkout, but we usually have someone cleaning on standby who would put you through
RM: Well where are they and why didn't they?!
Me: Unfortunately we are quite understaffed tonight as 2 people called in sick so it's been pretty hectic, sorry for any inconvenience
RM: Then your managers should hire more staff
Me: We have plenty of staff it's just that tonight's in particular called in si...
RM interrupting: That's not my problem that's yours! Look I'm not getting annoyed at you just tell you manager customer not happy
Me: I'll pass it on when I ca...
RM interrupting and pointing at himself yelling slowly: no dont say anything else, just shut up, CUSTOMER. NOT. HAPPY.
Me literally saying: Wow
Tldr; guy came at almost closing with a large amount of stuff, people called in sick, he didn't want to use a smaller register or self checkout and become self righteous af.