Violence, sex, horror and fantasy are great facilitators in films to pinpoint a scene as momentous. Suddenly, someone gets their head chopped off. Hey, that guy just took flight. Look, a first kiss! But critical moments don’t need to be nearly so complex. Sometimes, all that’s needed is a simple “What the fuck?”

Motion Picture Association of America regulations allow PG-13 movies one non-sexual usage of the f-word. The word can be used only once and only as an expletive. Arbitrary? Definitely. Hilarious if handled correctly? Of course.

Using the f-word more than once bumps the rating up to R, severely limiting a film’s audience and affecting box-office numbers. Many films that remain within the boundaries of PG-13 restrictions do not take advantage of the one-time cuss word allowance, and, often, it’s for the best. Imagine if Robert Downey, Jr. had dropped a hard “f” as Sherlock Holmes. How awkward would it have been if Indiana Jones had let one slip, or if Samwise had reacted a little too strongly to Frodo’s mood swings? Often, an f-word just doesn’t fit and would seem to be there mostly for shock value. But, occasionally, a single f-word is all the script needs for a scene to go from forgettable to significant.

Would Wolverine’s cameo in “X-Men: First Class” been nearly as characteristic and hilarious if he had told Magneto and Professor X, “go fornicate with yourself”? Would the backlash against Ron Burgundy have been as believable if the “Anchorman” star had instead ended his report with a tamer “Go fudge yourself, San Diego”? Additionally, would any other reaction have been appropriate to Emma Stone seeing Ryan Gosling’s quite f-word-worthy abs in “Crazy, Stupid, Love”?

The film industry is good at many things, not least of which is the ability to embrace restrictions (however strangely specific and nit-picky they may seem). Whether or not a 13-year-old is more or less scarred by a single use of this expletive or multiple seems of little consequence — what’s more significant is determining the proper place for it on the big screen.