Violence is funny, especially between friends. I mock hit my husband when he says something stupidly funny on purpose. I quote "One of these days, Frankie! Bang, Zoom, right to the moon!" (and gaze wistfully at the sky, because the more references you can do in one joke, the better). Between some of my girls and myself "Bitch, Ima cut you" or any phrase using the word "cut" is rife for giggles. It's funny between us because it's totally understood we all love each other and would do anything to not hurt one another. Counterpoint - injokes don't usually translate well to a broader audience. If the audience doesn't understand the years of love and trust behind the actions, it's a swing and a miss, quite literally.
Underdog violence feels good while being funny. We cheer when the weaker party lands that one blow on the cocky stronger party. Tom and Jerry cartoons are a good example. How else do you get past the horrendous beatings a little mouse puts down on the big, predator cat?
I don't think you can even have a discussion on why it's supposed to be funny when a girl hits a guy without understanding either above point, or the inescapable idea that women are weaker than men. Sure, there are several exceptions, but who today, when presented with the phrase "the weaker sex" thinks of men?
I am also a big fan and, at the same time, bitter enemy of switching sex to see if it feels the same with men and women in the other's places. It sure makes a point, but shouldn't be an end all to the discussion. That said, I'm going to start with the obvious. Take the recent Uma Thurman movie, with her palying a superhero who wigs out when her boyfriend dumps her and does funny things like throw a shark at him. Putting aside the fact that throwing sharks is the coolest thing ever and I want that for a super power despite how impractable it would be and how I'd cry myself to sleep each night because I love sharks, any male superhero going around wrecking up his ex-girlfriend's pad and throwing marine life at her would have to fast for 2 months on burning coals while sewing clothes for orphans who love sharks before most people would consider him even on the road towards repentance. Somehow I doubt Uma's character did that in the movie.
So what about the friends in Questionable Content? What if Marten was the girl and Faye the boy? Is this an in-joke between these two friends? I don't really know QC that well, as I find it as easy to follow as your average soap opera, by which I mean I used to watch maybe 2 weeks total in an entire year of Another World when it was on and I could follow it just fine. (And I loved it. I wish all soaps were smoking the same crack and not pretending to be realistic while bringing people back from the dead and enacting evil plots for love! PS Rachel and Carl forever!) Anyway, from what I can tell, there is that basic understanding between the two characters that they are friends, but there's also a sort of real fear on Marten's part that Faye might indeed react violently if Marten says something wrong.
Faye also seems to react this way to just about everybody (check out Starline's examples in her post), which makes it more of a character trait. As brought up in the discussion in the thread, this seems to excuse it a bit. In my way of thinking, this only excuses it if it's brought up. Maybe someone can point me to the story arc where Faye gets brings this up at counseling and wonders why her first response to things that offend or upset her is violence or the threat thereof. THEN it's a character trait. If no one notices that she does this all the time, except to cower or cut off what they're saying around her, then it's a failing and needs to be addressed. Having said that, this is an ongoing comic that seems to take forever to do story or character developement, like most comics that have a few panels with a punchline at the end. J. Jacques could just be getting around to it.
In which case, he'll also have to deal with Dora doing the same thing half the time. When both your main female characters threaten violence as a joke and sometimes as an actual solution, you really can't leave that sitting around. "Addressing" it doesn't mean solving it and everyone goes on happy happy, but let the cast notice it, even if they do nothing about it.
To bring this back to the wider picture, I think the reason this bothers me and so many others is that it is so prevalent. Like using rape in a storyline, there is nothing intrinsically wrong with the concept, as fiction is not an idealized world where everyone has no flaws and bad things don't happen. It gets to be a problem when it's used often and often used badly. Unless it is used as an injoke between friends, it's hard to see the "violent little woman" as anything other than playing with the "women are weak" concept. And if your joke rests on a negative stereotype, I fail to see how you're committed to destroying said stereotype. I adore breaking stereotypes for humor, but there does come a point where you're trying to build a complete character and the stereotype is near death, and the only thing that's keeping it alive is the stereotype breaker herself.
You see this often with "tomboys", who are so determined to not fit into the classification of girly girls, they perpetuate the tea parties with stuffed animals as typical girl behavior just to set themselves apart. I was a tomboy for certain, but I did realize at one point I could do what I wanted to do without having to make fun of the girls who swooned over the New Kids on the Block. I didn't have to classify myself as anything or anti-anything. Funnily enough, I realized this when the other hardcore tomboy in my 5th grade class seemed to think there was a competition between us for the most boyish and I thought that was the dumbest thing ever and we should be friends since we had so much in common.
In summary, perpetuating a stereotype in order to do anything that shows how against that stereotype you are = dumbest thing ever. Not that girls hitting boys is necessarily doing that, but it so easily can. Girls beating guys should not automatically equal comedy gold.