• saying "yeah", "uh huh" and/or nodding constantly when i am talking
• cannot enjoy comfortable silences
• are pretentiously religious/vegan/vegetarian/straight edge
• having no concept of personal space
• flaunting a particularly amazing/terrible grade for everyone to praise/feel badly for you
• asking questions you know the answer to
• in a fight: ignoring/avoiding the real issue
• overusing a word/phrase
• lying to get more attention or to harm others
• not taking responsibility or ignoring responsibilities
• stealing (all sorts, not just the physical sort of theft)
• ostentatious-ness

to be continued...