Answers found on Ask Reddit
1. Not taking personal responsibility for your actions.
2. Purposefully withholding important information from someone for your own self-preservation or selfish reasons.
3. Someone who goes out of their way to insult/criticize anyone or for the smallest mistake or inconsistency.
4. Disrespectful of people’s personal property in their home.
5. Queue jumping (or line cutting).
6. Never accepting blame for anything.
7. Consistently talking shit behind people’s backs.
8. Talking shit about mutual friends when they’re not around.
9. Being nice speaking to someone on their own but in a group situation showing off and being a dick to them.
10. “I know this sounds manipulative and rude, but (manipulative statement).”
11. Laughing at/making fun of other people’s interests and hobbies.
12. People who proudly state that they are assholes and have no intentions to change for anyone.
13. Being a dick to everyone else, then trying to excuse that behavior by saying “I’m just brutally honest.”
14. Mocking people for liking unpopular but harmless things.
15. Mocking people for liking popular but harmless things.
16. Never paying debts, even small ones.
17. Judging whether or not what you just said was a joke depending on the reaction of people around you.
18. Constantly telling people you are a good person.
20. People who aren’t able to be excited for you when you succeed; they always see other people’s success as a threat to their own worth.
21. Leaving your shopping cart in a parking space.
22. Playing music audibly on public transport when others can hear.
23. Treating wait staff badly.
24. Not being introspective enough to realize you’re the root of your problems.
25. Making fun of other people’s appearances, especially of things that aren’t easily, immediately fixable and cost money to do so (acne, crooked teeth, big noses and such.)
26. Taking any kind of criticism or conflicting opinion as a personal attack.
27. Punching down, i.e. treating those “below you” badly (be that at work, service workers, children, etc.) because you perceive yourself as higher status.
28. Being too proud to apologize.
29. Being rude because you “haven’t had your coffee yet” or some similar excuse.
30. Ever mentioning survival of the fittest as an excuse for being am asshole.
31. Changing lanes without using your turn signals.
32. Hurting animals.
33. When you mention something from a prior conversation and when they don’t remember having the conversation they’re like “I probably wasn’t even listening haha.”
34. Playing the victim when confronted.
35. People recording themselves giving homeless people money or food for social media.