It also depends on the type and what exactly it is. I've never actually seen Kangaroo Jack or Gladiator so I'm not entirely sure of the content. In fact, I've honestly never actually seen Babe: Pig in the City or Erin Brockovich. I actually read about these on sites called Screenit.com and Kids-in-mind.com . However, those kids I mentioned who wouldn't stop talking about breasts when I brought up the cleavage in Paranormal Activity... their mother might think the PG-13 rated The Invention of Lying is fine for them, because there's no actual cleavage or breasts in it (and if there are, it was brief). One of the reasons The Invention of Lying got a PG-13 was for sexual reasons, but that's because a guy told a woman "The world will end if we don't have sex!" (and they don't) and a girl gets a guy a "sex coupon" for his birthday, but he mentions he doesn't want her having pre-marital sex with him or her other potential boyfriend, and some other brief jokes. That kid just can't handle seeing a woman's cleavage without going nuts, but The Invention of Lying is rated PG-13 partially for sex whereas Paranormal Activity is rated R for language. However, there is no nudity in The Invention of Lying, nor anyone wearing anything revealing, so there's nothing to go nuts over. However, I bet that his mother wouldn't let him watch the PG-rated Aliens in the Attic because Ashley Tisdale's character wears a bikini in much of the film.
Adding to what I just said, Rugrats had much discussion (and sometimes action) of vomiting, excretion, and urination. I remember Angelica vomiting on her father, Chuckie being potty-trained (suggesting Spike should do the same when he urinated on a tree), and Phil, thinking Spike ate Lil, asked Spike to "throw Lil up". (I think Dil vomited on Chuckie in one of the movies.) That's what I mean by "violence" and "language". R-rated horror moves have a lot of blood and weaponry, and sometimes swearing, but it's not disgusting like Rugrats. For instance, I don't think even my mom can handle that (she loves The Angry Beavers, for instance, but she told us to skip the episode with the "Loogie Hawk", which even grosses me out) but she considers Pulp Fiction a good film to watch (and I do too). Some people are just more tolerable of bloody violence than vomiting/excretion/urination violence.
Thing is, as much as my mom doesn't want to believe it, I don't watch cartoons, especially ones aimed at such a young age and, for that sort of reason. I think it's disgusting and wrong. It's rated TV-Y7 for a reason. Sexual references are the type of thing to watch Family Guy for, but again, Family Guy makes blatant sexual references for a laugh. Winx Club simply has the girls show a lot of skin as part of their normal attire and no one questions it (though I do remember one episode where they were going to Sparx and Palladium said something like "You can't go there wearing bare midriff tops!" and as he put coats on them, Griselda said, "If it were up to me, this would be the year-round dress code!" But that's just a brief joke and I paid little attention to it).
I know. I said, "It doesn't really get scary and there's nothing violent until the end" and she actually told me not to tell her what happens in the end. It's too bad they won't be able to see what I was talking about now.