I would agree with another viewer who wrote that this movie recalls the offbeat Melanie Griffith/Jeff Daniels comedy, "Something Wild," in which a rather eccentric free-spirit hooks up with a conservative and very orderly young man, and the two pose as a couple and basically, her personality gradually has an effect on him. He looses up and learns to enjoy their short-lived tryst. That is exactly what happens here, except insert convenient store-robbing eccentric, Alex (Rosanna Arquette) in Melanie Griffith's role, and super-cautious teen, Lincoln (the name is no coincidence, played by Devon Gummersall) in Jeff Daniel's part. This movie even shares the same twist and abrupt genre change where the creepy, violent boyfriend suddenly shows up in the end and things end up quite badly. Only, here, instead of it being Ray Liotta playing a throwback to 1950s film goons, it's Peter Greene.
The story is about a teenage kid who is in his own little world. He has some sort of fascination with death following his brother's suicide, and his parents have disconnected, too, behaving quite strangely (the mother is convinced Christmas will be arriving shortly, despite it being August). Then, on a night out with the "guys" (one of whom is played by Jason Hervey of the Wonder Years) trying to buy them beer, he runs into Alex who decides to kidnap him and his friends car (with his permission of course), and they take off for mini-adventure across the deserts of the West Coast, robbing convenient stores in Robin Hood sort of fashion and of course, indulging in the routine self-discovery as each asks more about the other's life. But, Alex has left behind a partner in her trade of theft, and he isn't going away easily. Although, we're not consistently reminded of him or anything as in repetitive flashback or cutting over to his point of view. At least this much was done cleverly.
'Do Me a Favor' (aka Trading Favors), is a mostly underdeveloped story of criminal mischief and self-discovery that lags quite a bit for the first half of the film, but delivers the goods a little to late once Alex and Lincoln arrive at her home out in the middle of nowhere. By the time the filmmakers give you enough stimulation, the film is unfortunately, almost over. I would recommend that if this is the sort of story you're in the mood for, and despite Rosanna Arquette always giving a good performance (even in a poorly written film), I would still recommend catching this in its best form, "Something Wild."