James Jerlecki can’t tell me exactly how his new app is going to be useful, but he thinks teens are gonna love it.

"My sister is a teacher and works a lot with teens," he says, "and they want her to respect them, but they are afraid about what they share." Jerlecki’s sister wishes there were an open forum where students could share thoughts and ask questions about things like drugs, sex, and "the popular kids" without worrying about their reputations.

This kind of space — which is anonymous, yet personal — doesn’t really exist outside Alcoholics Anonymous. So Jerlecki built Rumr, an app for iPhone and Android that lets you carry out anonymous group chats with friends. The idea sounds like an oxymoron, but is more nuanced than you might think. Each group chat has its own buddy list of who’s involved, but everybody inside the chat window itself remains nameless, designated only by different colored bubbles. In other words, you’ll know which ten friends are in your chat, but you won’t know who’s saying what. The more people there are in the chat, the less likely you’ll know who’s who.

"We’re in a world where most everything we do is public," says Jerlecki. "You can be more of yourself where you aren’t as concerned about crafting the right message," he repeats, echoing the mantra uttered by every ephemeral / anonymous app company that came before him including Whisper, Secret, Snapchat, and Confide. Rumr hopes to differentiate itself with its slogan, "turn off the lights," a phrase that evokes memories of sleepover parties and summer camp cabins. But just like in your friend’s basement, where you might speak more freely amongst friends as you gaze upwards at the ceiling, telling who’s who in Rumr isn’t as hard as you think. Rumr isn’t Secret, where a revealed identity could very likely cost somebody their job.

Despite its name, Jerlecki says that keeping groups small inside Rumr should keep things fun — instead of inciting panic like Ask.fm, where actual rumors run rampant. Another anonymous chat app, Yik Yak, had to shutter access to middle school and high school students because of cyber-bullying concerns. "I want to send this message to an audience that I can connect with and that cares about me," Jerlecki says. "It can solve real problems." What’s perhaps most interesting about the gamut of anonymous and ephemeral chat apps is that they create new behaviors amongst users, so it’s almost impossible to predict how people will use it. Rumr, for example, supports group chats of up to 100 people, which could elicit entirely new and bizarre scenarios for communication. Had someone pitched me Snapchat, an app that "let people be themselves with disappearing photos," I might not have seen a use for it beyond sexting.

"I think for something like this, use cases will present themselves as the network evolves," says MG Siegler, a partner at Google Ventures who invested in Secret, Confide, and Rumr. "I could rattle off some [use cases], but I think anything I say, the community will ultimately prove wiser than myself." And Rumr’s community isnt just about teens. Jerlecki says that his team has used the app internally to debate feature ideas, and his group of friends has used it to trash talk each other about March Madness. "We’ve found that the magic number where it really becomes anonymous is around four to five," Jerlecki says. "Then, the anonymity increases and the fun starts to happen." But he can’t come up with many fun stories about using the app. Rumr’s use case is as fuzzy as its panda mascot.

Rumr certainly looks like a bandwagon-jumper hoping to cash in on the anonymous app train, but if past successes in the space have been any indication, an app's users will be the true measure of its value as a tool — not its slogan or feature set. Or maybe the anonymous chat trend has simply jumped the shark, spewing out "apps teens want" when teens aren't really asking for anything.