Laugh, and the world laughs with you. Choke your kid, and the world still laughs with you. Under the right circumstances.
Watch any episode of
The Simpsons, and there's a good chance you'll see Homer yell at Bart and grab him around the throat. You can laugh safe in the knowledge that no one is being harmed. Watch an identical scene in a live action comedy, and there's a good chance you'll feel mildly uncomfortable, because real, identifiable people are simulating the act. But again, you know they're acting, so you aren't too bothered by it. See that same scene happening outside your living room window and you'll be on the phone with a 911 operator in seconds.
Safety in fiction. The knowledge that it's not real lets us comfortably cheer for thieves to make their big score; laugh when a character says something bitingly mean to another; and enjoy the drunken ramblings of a pathetic nuclear safety inspector (or whatever Homer's job is) without feeling guilty for enjoying it. Fiction is our release valve.
I've been watching a couple TV shows lately with characters whose behaviors would be inappropriate in the real world. House is one. It's a great, fantastic show, and Hugh Laurie owns the character. But does anyone think House would've held a job for more than a month in the real world?
Not a chance. It doesn't matter how brilliant you are if you're so difficult to deal with that no one wants to talk to you. But because it's fiction, his jerkish behavior is funny, and the show is very popular. We, the audience, can fantasize about being like him, about saying exactly what we want, with no governors on our behavior (but of course, always in a witty manner).
Another (though defunct) show I've been watching has a main character that would actually be difficult to like:
Veronica Mars. Veronica's a good person, but she's manipulative and a taker, and she's not above using her looks to get what she wants. But because she's amusing, and because we know it's fiction, we can watch the show and still like the character even when she's using people.
I mention these shows in particular because a lot of writers have a fear of creating protagonists who are less than saints. They worry that no one will like their hero if they do this or say that. The truth is, you can like damn near anyone in fiction if the writing is skillful enough. Think about it, in real life, would you really want to hang around Dexter? Or Al Swearengen? Or even Gregory House?
Make your character someone you like, even if he's arrogant or a killer or a petty thief, and there's a good chance we'll like him, too.