Pretty much any time you do or say something without considering the feelings of other people. However, rudeness in unintentional. Being an ass is being intentionally rude. The rudest thing I can think of are back handed compliments. Like, this one girl told me that I could be pretty one time.
I think it's rude when someone just outright does something with the purpose of offending someone. Of course, that's when someone's meaning to be rude. I think it's rude when someone is just generally inconsiderate.
If I tell you a genuine comment about you and you quick respond to me like I'm lying and it's not true. Just say "Thank you" :icon_sad:
Sarcasm....well, maybe it's not rude but something about it irritates the CRAP out of me. Gah, I HATE sarcasm.
Mate I gotta start watching 30 rock that's hilarious and I keep seeing ads for it. NOT REPLY TO MY FUCKING TEXTS! (okay my phone is off and I'm drunk to deal with this shit but still! fukcing annoying!)
Not sure if these constitute as "rudeness" as more so things I just dislike, but yeah: I loathe it when people are a complete jerk to you, but the minute you even remotely criticize them or make a simple observation about them they get their undies in a bunch, or they brush off their very spiteful comments as a "joke" to cover their behinds. I think that's pretty darn rude, at least be mature enough own up to what you said. Not having decent manners, even simple as saying "please" and "thank you". I'd at least hope you did not grow up with wolves. People with vast, really unnecessary superiority-complexes. Great, you can do a few things without totally failing and mucking up. Please demonstrate to me the other 9000 things you claim to be good at, such as x, y, z activities, being great at a, b, and c, things, and how totally AWESOME you are and how you are so much cooler than everyone else. Relating to the one above, when you are explaining things that you enjoy doing (for me, it's art) to someone and then a person who has nothing to do with the conversation butts in and tries to say how much better they are at that activity when they really aren't. In essence, stealing your thunder without justification. (This has happened to me before, I had been giving a friend of mine advice on how to draw portraits and then another mutual friend butted in and said "Yeah, I can do portraits." But did not give any advice to the friend on how to draw them nor demonstrate his ability in that area). And probably many other things that people do. :dry: I'm pretty sure there are things I do that some would consider rude. But that's life.
Talking on the phone while at the counter/register. I find this incredibly rude. I'm not a machine. Either finish your phone call before coming up to the counter, or hang up and get back to whoever you're talking to later. Hell, even ask them to hold on for a minute, and put the phone down. Just don't keep talking on it.
People that don't have manners, and think they're better than everyone else and think their the fucking king of the world