You may scoff at that coworker who brings a newspaper into the bathroom at work, but we know the truth about you now. According to Atlanta-based AIS Media, a survey of 500 people found that 27% of Americans report using mobile devices to check Facebook while in the bathroom.

“While it may seem humorous to survey people about their Facebook usage while in the bathroom, the results underscore the proliferation of consumer social media usage and their strong need to stay connected,” said Thomas Harpointner, CEO of AIS Media. “For businesses and brands, social media offers an opportunity to engage potential customers like never before.”

He’s right. It is humorous to survey people about Facebook bathroom usage!

But seriously, this is the kind of study I absolutely love as it proves something you sort of suspected in the first place. Quoted in the press materials announcing the study, Edward E. Rigdon, a marketing professor at the J. Mack Robinson College of Business at Georgia State University, points out, “I imagine most people carry their phone with them, in pocket or purse. People receive emails on their phone alerting them to Facebook messages or postings, and many people respond by reflex.” (And others just go hide in there with their phone to get out of work.)

And for marketers, the lesson is simple. Says Rigdon: “This study illustrates one of the … ways in which marketing is changing — it is becoming more ubiquitous. Marketing is everywhere, and anything can be marketing.”

Wouldn’t this be the perfect opportunity for makers of hand-sanitizers to reach audiences — and guilt them. Tagline: “We know what you’re doing, you filthy thing you.” Perhaps those Charmin bears could set up a Facebook profile. (They don’t exactly have a favorable presence on Facebook as it is.)

What’s more, AIS found that potty-poking was higher among women. Some 54% of female respondents admitted to doing it compared to 46% of male respondents. Of course, it doesn’t take a biologist or anthropologist or psychologist to point out that it’s much harder — and weirder — to “Like” something while standing at a urinal. (Though that’s not to say it isn’t done.)

The study raises a host of other interesting questions. Would these numbers have been higher if so many people weren’t playing Angry Birds in the bathroom stall? Which phone platform (iPhone, BlackBerry, Droid) is preferred among toilet-texters? How many people have used Foursquare to check in to a bathroom? And, most important, will you ever touch someone else’s phone again?