Until I got to the Varga Girls.
Alberto Vargas was a Peruvian artist who became world famous for his Varga Girls, pin-ups painted for Esquire Magazine during the 1940s, especially during the war when they served as "morale boosters" for the American troops. Vargas later painted Vargas Girls (the name was changed because of a lawsuit, I kid you not) for Playboy Magazine. Wikipedia has a good article on him. I could links to some galleries of his works, but all of them would toe the line for being NSFW. Just put "Varga Girl" into any search engine and you will, ahem, get the picture.
The specific picture that I believe this image is modeled on is on a website about an American WW2 searchlight battalion. The website was started in 1996. (The date is important.) See this link, about pin-up girls often seen during WW2 (the link is safe), then scroll down to the bottom of that article, before the one about Fort Carson. See her?
"The quintessential Varga girl," reads the caption. (This, too, is important.) Now, we take that image and flop it, reverse it left to right, and we have:
Now, we put the Quinn alter ego next to it, and compare.
Here's what I think happened: A staff artist at MTV got the idea to draw Quinn as a Varga Girl (or perhaps one of the Daria characters, but the Varga Girl idea was there at the start). The artist gets on the Internet in 1997 or 1998 (1-2 years after the WW2 website above started) and did a search for "Varga Girl." The "quintessential Varga girl" appeared, and the artist immediately linked quintessential with Quinn. Thus the picture was born.
However, the artist wanted to be clever and not look like he/she had copied the pic exactly. The pic was flopped (click on "flopping" below in Labels for other discussions of this technique) and a few things were added, like the frilly bed and the phone (to keep Quinn from pulling off her one-piece outfit).
Pay attention to the posture of the model, the turn of the head, the position of the right hand, the position of the legs, the high heels and where they are. Bingo.
And there you have it: Quinn the Varga Girl. The MTV artist's little trick has been uncovered. Nice one.