Those of you defending Lester are both repulsive and totally predictable
It's a middle aged Dad who starts working, quits his job, and basically regresses to age 16 because of a girl his own daughter's age. The dark joke at the center of this movie is how much we as Americans love jailbait--it's not to give you *beep* pervs out there a thumbs up for creaming yourselves over high schoolers on the bus.
Those of you justifying him just want a movie to validate drooling over teenage girls who would probably be repulsed by you, or creeped the *beep* out a grown man is all but get a hard-on in public when he sees a kid.