h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Turn small things into major conflicts. Never let anything go.

Say things to deliberately hurt, such as, "You're just like ___"
Deliberately try to make the others feel bad, guilty responsible where unwarranted in making personal attacks.

Use silence and withdrawal, behaving in a cold and unwelcoming manner. Never say sorry or excuse me or please.

Interpret others motivation or behavior without having a conversation with them.

Expect things to be like they were somewhere else or with somone else.

Talk too much and too long on the phone or in person.
Don't take messages or forget them.

Bring up old arguments of yours or others.

Become addicted to something like being right, cleaning or to a substance or activity.

Keep a different day-night schedule and have no respect for others.

Make threats about anything; like to leaving - breaking the agreement or resorting to threats of violence or emotional blackmail.

Have friends over that are rude and disrespectful to others.
Have a lots of unannounced guests. Or the opposite not allowing or welcoming others guests.

Not to mention prolonging the issues over days, weeks, months until that idiot grovels for apology.

Seriously, forks, settling the arguments before going to sleep *is* generally a Good Idea.

Most importantly, make sure that you always disagree with someone, even when - especially when you're wrong