![The Jerk mistake picture](/images/screenshots/94000-94999/94941_sm.jpg)
Continuity mistake: When Navin is at the gas station and is being shot at by the sniper, take a look at the arrangement of the oil cans on the rack beside him. One of the cans in the middle of the rack changes color from pink to purple, and some labels turn, between shots.
Answer: Navin self-applies the "Jerk" epithet early in the film, using it not in the sense of someone obnoxious or mean (as it is used in most cases), but in the sense of a stupid person. He's saying he blames himself and his lack of intelligence (though, as you say, it is usually simple naïveté) for ending up where he is (broke, homeless).