Interesting. I only knew the rule about it referring to intercourse. I suppose a lot of it will also have to do with the particular reviewers as well. I looked at the guidelines and saw this " A motion picture’s single use of one of the harsher sexually-derived words, though only as an expletive, initially requires at least a PG-13 rating. More than one such expletive requires an R rating, as must even one of those words used in a sexual context. The Rating Board nevertheless may rate such a motion picture PG-13 if, based on a special vote by a two-thirds majority, the Raters feel that most American parents would believe that a PG-13 rating is appropriate because of the context or manner in which the words are used or because the use of those words in the motion picture is inconspicuous." So you're absolutely right. Didn't they make sure to only drop 399 'F-bombs' in the South Park movie because they believed that 400 would be the threshold to get an NC-17 rating? Whether that was ever a guideline or not is beyond me, but it's funny that they would do such a thing. I also remember before the PG-13 rating even existed, several PG-rated films used several expletives and G-rated films could get away with a lot more in terms of violence (IE Planet of the Apes originally had a G rating). Then when PG-13 was introduced there was a real separation where G was considered 'for kids' rather than 'general audiences'. Thanks for the lesson.
@clousems