You know why do I suddenly remember all the YouTube video's saying Pixar hand a ton of subliminal messaging in it (which there examples of 1mm blurs in the grass that looked like something were "subliminal messaging"). This is the problem I always like to point out how can you decide what is over the top and whats not? For example I at the age of 9 watched Stephen Kings The Shining which is to this day still in the top 10 scariest movies of all time list I believe. What did I think of the move? Scary? Pfft no, I thought it was a very well done movie a far cry of all the crappy 2bit horror movies and cheap thriller movies that seem to hit the market now like its the best thing since sliced bread. I grew up reading Manga that was rated OT (16+) and every now and then AO (Adult Only 18+). I never came out emotionally scared? Heck how many 6-10 year old kids play Halo? or CoD for that matter, they love there CoD.
As I said before 90% of all horror, thriller, action movies, are more like comedies now anyway.
So whats over the top for PG-13 in my opinion, lets just say the area starts to gray around R rated I don't think I need to go in much detail to get my point across as to what I mean by that, but again that's in my opinion. I don't know what it is or if it's only in American but they really like to shelter people.