As we all know from the recent controversy over the initial R rating for the documentary "Bully," the Motion Picture Assn. of America finds bad language very scary. It is almost entirely unperturbed by extreme violence, which is why so many movies, most notably "The Dark Knight," can still receive a PG-13.

But when it comes to drugs, the MPAA apparently isn't sure what it thinks anymore. It seems especially confused about what kind of drug use can be depicted in movie trailers, the primary means studios have of luring young people to see their films.

Let's go to Exhibit A: the new trailers for "Ted," an upcoming R-rated comedy from "Family Guy" creator Seth MacFarlane. For the past few weeks, the Internet has been abuzz over one uproarious trailer for the Universal Pictures film, which chronicles the wacky co-dependent friendship between Mark Wahlberg's John and Ted, a foul-mouthed, sex-obsessed talking teddy bear.

The trailer is a so-called "red-band" trailer, which can be crammed with foul language and crude sexual humor. Because of restrictions imposed by the MPAA advertising administration wing, headed by Marilyn Gordon, it's almost impossible to see red-band trailers in theaters, although they are widely available on innumerable websites. Green-band trailers, in contrast, are generally scrubbed of most offensive content and made available either for "all audiences" or "appropriate audiences," the latter being audiences in theaters that don't contain a significant proportion of children.

In recent years red-band trailers have flourished on the Internet, where they are a prized marketing weapon for studios eager to impress kids by showing just how much raunchy sex, drugs or naughty language is in their R-rated comedies. One of "Ted's" red-band trailers on YouTube has been viewed more than 4.3 million times.

YouTube is a favorite pit stop for my 13-year-old son and his pals to watch movie trailers. The red-band "Ted" trailer is almost gleefully explicit, showing Ted unleashing a volley of F-bombs, simulating a sex act with a supermarket check-out counter scanner and taking a big hit from a bong full of pot.

The trailer is clearly R-rated and approved for viewing only by "mature audiences," a warning that obviously is not especially effective in the age of ubiquitous Internet access. But what has really raised eyebrows among movie marketers is the green-band trailer for "Ted," which is available all across the Web and is supposed to have far less explicit content.

The green-band trailer for "Ted," which is approved for "appropriate audiences," is missing most of the red-band trailer's explicit humor. But here's the eye-popper: We still see Ted, sitting on a couch next to Wahlberg's character, smoking a bong. The shot has been edited so that we don't see him inhaling. But we do see Ted taking the bong out of his mouth, tamping his hand over the top, and exhaling a cloud of what is obviously pot smoke. As one rival marketer put it: "I'm shocked, and I mean shocked, by how they got away with that."

Until now, pot references were clearly verboten in green-band trailers aimed at what is known as "appropriate audiences." The MPAA's own advertising guidebook says that green-band trailers "shall not include excessive or graphic images of violence or sex, excessive profanity, or drug usage."

The current red-band trailer for Adam Sandler's upcoming "That's My Boy," for example, depicts Sandler taking a hit from a bong in a strip club; the scene is not in the green-band trailer. In the red-band trailer for 2008's "Pineapple Express," Seth Rogen is smoking a joint, exclaiming, "That is good weed!" In the green-band trailer, he coughs up a puff of smoke, but no joint is in sight.

Nancy Meyers' 2009 film, "It's Complicated," earned an R rating solely for a scene in which Steve Martin and Meryl Streep smoke pot in the bushes at a party; to show a snippet from the scene in its green-band trailer, Universal had to digitally remove the joint, leaving us to wonder exactly why Martin was holding his arm in the air with such a curious smile on his face.

So why has the MPAA allowed Universal to show a bong full of pot in its "Ted" trailer while making everyone else cut out their weed references? MPAA press reps said Gordon wasn't willing to talk. No one at Universal would speak on the record either. The same goes for marketers at rival studios, who don't want to cause problems with the MPAA.

Marketers complained to me that there are so many inconsistencies in the MPAA ad policies that it's almost impossible to tell whether the bong joke represents an actual change in enforcement, a simple blunder or an experiment to see whether it draws complaints from anti-drug activists. Universal insiders say the MPAA approved the green-band "Ted" trailer to run in theaters only in front of two R-rated comedies, the studio's own "American Reunion" and Paramount Pictures' upcoming Sacha Baron Cohen film, "The Dictator." It has not been shown in front of any PG-13 films.

But on the Internet, it's everywhere. As a parent, I want to know where the MPAA stands. When you have a 13-year-old who's in a school with a zero-tolerance policy for drug use but lives in a pop culture where drugs are routinely embraced and celebrated, you'd hope that the MPAA would act as a sensible traffic cop. But as matters stand now, there is zero transparency to MPAA dictums. And when the people who run the ratings system refuse to explain how and why they've made key decisions, it's the parents who end up having to police things.

I know the MPAA is between a rock and a hard place.

After all, America itself is full of ambivalence about the war on drugs, with President Obama saying he's against legalization and evangelist Pat Robertson in favor of marijuana decriminalization. But when it comes to advertising messages fit for kids, the MPAA seems so foggy and befuddled that you almost wonder if, well, it has been indulging.

If the MPAA has a new set of rules, it's time to share them with all of us puzzled parents. Seth MacFarlane is getting a lot of laughs from his pot-smoking teddy bear, but if the MPAA thinks that 13-year-olds are an "appropriate audience" for a bong gag, I'd like to know why.