While the childish antics of Brennan (Ferrell) and Dale (Reilly) are initially nothing short of hilarious, their insults and bonding montages start to get a little tiresome. By the time the two boys have successfully ruined their parents' life, the movie hits a bit of a standstill, rolling from one bit of repetitive physical comedy to the next.
Luckily the film saves itself in the end with new found maturity that gives us this quote after Brennan loses his job:
"I'm so scared right now. I'm just gonna do what's sensible, I'm gonna file for unemployment. Then I'm gonna try to get a job at Enterprise Rent-A-Car, because they got an excellent corporate structure and they...they give you the tools to be your own boss."
And that points to the reason this movie actually works for me. While the physical comedy is silly and a little amateur, the subtle bits of dialogue involving popular culture and creative use of the many words for male genitalia actually save the movie. This seems so backwards. It's usually those pop culture references that ruin films, dating them with overused observations about today's world (hey everyone, let's make a movie about a cell phone! We'll call in 88 Minutes but the movie will be much much much longer than that!). In this case the pop culture is so far out there that it struck me as very clever. Likewise, I think, with all the poop and fart humor. It's just different enough that it surprises you. And, most importantly, makes you laugh.