New York City based startup, Fast Society just released a shiny new iPhone and Android app that’s “Built to Party” just like the hot, slutty girl you had a crush on in high school.

It’s hot because, well just look at it: it’s sexy, bright purple, easy to use, photo sharing friendly, conference call ready, location enabled via Google Maps and it even lets you shout short, recorded voice messages to your friends within the groups. Unlike the app’s first iteration, groups can now last forever and you can have up to 5 “teams” at once.

“In a time when teenagers are getting kicked out of school because of Facebook posts, FastSociety is a place to interact in ways that used to be fun to do online. Texting is the last safe haven and we wanted to create something that is edgy and dangerous. We’re not your mom’s startup. We’re young and aggressive. We want to be the MTV of startups. The day we start catering to grandmas or hunters, we’re dead,” says Fast Society’s Matt Rosenberg.

It’s a slutty girl because, well trust me, this app likes to get around.

photo 1 220x330 Why Fast Society is the hot party girl of group texting appsThe latest build of Fast Society is much more focused on the in-app experience. While users without an iPhone or Android can still participate in the conversation, they miss out on a lot of fun features like audio messages and location sharing, so they may start feeling like their riding the short bus. iPhone and Android users can switch between push and SMS at any time, but texting within the app is totally free.

“We think the future is going to be within the app. It’s a beautiful application and it’s just a matter of time before everyone has smartphone,” says Rosenberg.

Other features of note: The app’s “Go back in time” feature is cute if you want to remember an epic evening with friends or a long-drawn out in-app romance.  If you’re creating a group and want other people to manage the guest list, you can make invites public to your friends via Facebook and Twitter. You can then accept or decline RSVPs inside the app over teams you manage.

The “Rally” feature lets people create new groups on the go from existing teams. I imagine new team names like “Big Titties,” “Party at the Moontower,” and “Don’t tell mom we went to the strip club.”

The group messaging space is obviously hot right now, with other apps like HeyWire and Kik gaining momentum in the international space. Unlike GroupMe, a New York City based start up, Fast Society isn’t built on Twilio, it’s built on top of its very own platform, which Rosenberg says gives the app huge cost saving advantages and added flexibility. “We spend less in a year than they do in a month. GroupMe is like baked beans, and we’re like gaspacho,” says Rosenberg.

And unlike Beluga, Rosenberg is staying away from Facebook. “We’re not trying to be a social network,” says Rosenberg. “Unlike Facebook, Fast Society is designed for a single group.”

Fast Society was born out of a Bloc Party concert in 2009. “People go out with their friends in short term groups and we wanted to create something that worked on any platform for this need,” says Rosenberg. Rosenberg teamed up with friends from American University to officially launch the app in September 2010. “We’ve been working on this new version of the app ever since, it’s going to blow the other group texting apps out of the game,” Rosenberg says.

While GroupMe has raised a cool $10 million in funding, FastSociety has only raised $275,000 in seed capital from Eniac Ventures, Quest VC, and hedge fund investor Jim Pallotta, but they have much lower costs and are hardly strangers to bootstrapping it.

The app is U.S. only for now. Expect a Windows Mobile version soon. Need more proof of hot party girl status? Check out their latest video promo:

Fast Society Version 2 Launch from Fast Society on Vimeo.