No, it isn't about Daria's foray into pugalism. This was a very revealing episode, as a seemingly insignificant item--a cardboard refrigerator box--dredges up painful repressed memories.
It opens strangely--a dark screen, a crash, a honking horn, a man's voice. Then the show starts. After a new refrigerator gets delivered to the Morgendorffer house, Daria seems oddly attracted to the empty carton. She knows it has something to do with a memory, but...what?
It seems that Daria overheard an argument between her parents concerning her at age five, and it's been in her subconcious since. With Quinn's help ("I remember that fight. The deep emotional scars have been with me for years and still hurt to this day. Do we have any juice?"), she pieces together that she was the reason for the quarrel that caused Jake and Helen to yell at each other and Jake to leave all night. Jake's present unexplained abscence (due to a branding meeting; Quinn thinks it has something to do with cows!) and the box's prescence exacerbate the matter.
Daria keeps rescuing the box from the curb and eventually seems to start to snap; she regresses and climbs into it. Here we learn that as a child a box was her "happy place" when her folks began to argue (I'm not sure if it was this one instance or during all their fights, but I suspect the latter. I was reminded eerily of the Pinky and the Brain short "Project B.R.A.I.N.", with the water-filled isolation chamber at this point.)
Jane thinks Daria's nuts ("The neighbors are starting to talk." "Good. Soon they'll start making crude cave drawings, and civilization will begin anew."), Helen and Jake are deeply concerned, and Quinn, who also remembers the quarrel (though whether she's too ditzy or too well-adjusted to be bothered by it is anyone's guess) is...oddly sympathetic.
Daria finally cracks up and takes to the road, on her way to see Tom at the cove, and causes an accident on the highway. The scene where Jane comes to meet her--looking very psychotic with wet straggly hair!--at the diner and she embraces her friend is very poignant (and uncomfortable for Jane). Daria hides her face--is she weeping? This may be the moment Dariites have waited for since at least 1998--our favorite deadpan darling opens up and goes on either a crying jag or a Jokerlike laughing fit.
Jake and Helen assure Daria that she was merely a subject in what I'm sure is a long list of arguments between the Morgendorffers, not a cause or a rift in the marriage. Like most intelligent children, Daria tends to become frustrated and act out passive-aggressively against the world and cause trouble with authorities (I can relate). Socialization isn't her strong point, and forcing her into it only aggravates her hostility. Jake, not being the most patient parent in the world, doesn't help matters by losing his temper in times of stress, although it was wise of him to go to a motel that night and cool off rather than take it out on Helen and the kids with violence. The biggest mistake here was burying the matter and not talking it over with the girls, hence Daria's long-buried trauma.
Note how Helen well-meaningly emasculates Jake to keep him from saying the wrong thing ("I think you broke my foot!").
Anyone count how many times Quinn uttered the word "freaking" as she hauled the box to the curb again?
Nice to see how Quinn showed she cared about Daria in the end by putting the box in her room, just in case. Although she won't admit it, she watches out for Daria more--she's openly admitted to being her sister (though everybody but Sandi knew that and were just being polite), she suggests a scholarship option in "Prize Fighters", she frets over the thought of drifting apart in "Aunt Nauseum" --and really does consider her more than that crazy stranger who lives in that padded room down the hall.
This may be the last Daria epsisode we'll see in a while, maybe the last ever, and it was a nice finale. Though it would have been a little better if there were more contrast between the way Lawndale and Highland (in the flashbacks) was shown; couldn't they have made it look a little less bright and more filthy? Maybe a cameo from the young Beavis and Butt-Head. That would explain much of Daria's trauma right there.
The line that got the biggest laugh from me came near the end--Jane promises to show the new students which showers haven't been peed in for twenty bucks. Daria assures them she was just kidding. "They've all been peed in." Dear God, I hope they were talking about the men's showers....

I didn't write reviews of Daria for the last couple of weeks because I missed last week's ep and there really wasn't much to say on "Prize Fighters", since it's not the sort of thing we haven't seen before--Daria writes an essay for a scholarship to college, then frets about it because she learns Jodie and Upchuck are up for the same deal and, worse, the admissions board takes her serious and well-thought essay on how she'd change the world (by reorganizing the ecomony) as a satire. Which is where I can relate--if you have beliefs and stand up for them, people take you as either a madman or a joke. Daria is also concerned about her failure to go fire-and-brimstone over the Wizard corporation's old-fashioned hiring policies as being a sign of losing her edge, but is forced to accept it as a consequence of just growing up (which recalled the discussion of Jodie's pragmatism in "Partner's Complaint".) Plus a whole subplot on Jake and a bungle involving bulk-rate mail-order weiners.