I think the reveal that Charlie was a registered sex offender for peeing in a playground at midnight with no kids around was hilarious.

But I feel like the laugh would have been even greater if they had alluded to him not being able to find a job anywhere and that Aniston was the only one who would hire him, before actually telling the audience why.

For example, it would have been curious as to why he put up with aniston the whole time and then had it been revealed by Bunk in the interrogation scene.

Having said that, that sub-storyline was one of the funniest in the film.