Now, whether or not the film actually deserves the R rating, the MPAA makes a bold move here in singling out one specific instance of crude sexuality ... not even a whole scene or anything building up to that scene, but rather, a single remark is the sole reason for the R rating. This implies that everything else in the film is hunkydory. It provides little assistance to the potential parent trying to decide if this film is alright for his/her child to view. "Thematic elements" would even have been better here. I can actually see how this film could receive an R rating -- I'm not opposed to that. It's the implication that the R rating comes from a single phrase spoken as an aside that really had little to do with the plot of the film.
I don't get too upset when I see these explanations, because it's mainly just funny. However, if I were one to determine my movie watching based on the rating of the film, this sort of explanation would not satisfy my requirements. If I were going to miss out on a film, it would have to be for a better reason than "a crude sexual remark." How the MPAA ratings still hold any sway over people's viewing habits, I just don't understand.