WASHINGTON, D.C. (WUSA9)--Remember when Kim Kardashian snapped those risqué photographs of her own behind? The pics went viral and even launched a new term: "belfies." That's short for "butt selfies."

Now, celebrity backsides have created a dangerous trend: more and more women are turning to illegal, black market injections to increase their size. And some are suffering dire consequences.

Women are choosing these injections over implants because of cost and convenience. Initially, there's very little recovery time and the price is usually a few hundred dollars compared to as much as $10,000 for implants.

"It's kind of like your wardrobe now. It's just one of those things you do. I don't wear a suit and a tie. I got a booty. Like that's what I wear to work," said "Sara." She's 31 years old and wanted to boost the size of her behind, so she turned to an option cheaper than implants and illegal: silicone injections.

"If you're in a club with a hundred women, we'll say 80%, 80 women will actually have them done, so it's kind of like, you know, you have a competitive edge," she said.

But her injections led to problems. And she's not alone.

"Over the last couple of years, and certainly in the last six months, I'm seeing a rash of people who've had these injections done who are coming back with problems," said Dr. Emeka Onyewu, a Silver Spring, Maryland plastic surgeon.

Not only are these silicone injections illegal, they're often mixed with materials that create horrible, disfiguring reactions.

"This dark skin feels like leather," said Dr. Onyewu, pointing to a photograph showing a woman's buttocks with dark, textured skin. "Like a leather purse."

He added, "We've heard stories of motor oil being mixed with them, we've heard fix-a-flat, hydrogel. These are substances that go to the kidneys and destroy them. Goes to the liver and destroys them, eats through the skin."

They can also lead to masses of silicone that have hardened and migrated. So firm, Dr. Onyewu must work to soften the tissue enough to remove it.

Said Dr. Onyewu, "If you tried to go in now and surgically remove it, you couldn't even get a knife through it, that's how hard it is. That's how thick it is."

Even more alarming: these black market injections are being done at pumping parties held in motel rooms, private homes and spas.

"Most of these have been done underground," said Dr. Onyewu. "These girls get together with one source and that source, with drinks and food and everything, they sort of party and they get these injections done. There's a shroud of secrecy around it. It's hard to get into these parties. You have to be invited by somebody who's had injections done before."

Recalled "Sara," "It was a group of us. Maybe a few of my girlfriends and I, we actually heard about this person, so we just went together, got a little hotel room and had a little girls' night."

WUSA9 found one ad on craigslist and asked for more information. Minutes later, we received a price list from an injector in Buffalo, New York claiming to work with lots of "girls from DC." This person promised results would be "immediate and permanent" and was even willing to come to DC for a "$300 travel fee."

"I don't suggest it," said "Sara," reflecting on her 'bargain' injections. "I guess the main reason is you never really know who's doing it and what they're actually injecting. You hear a lot of horror stories now with fix-a-flat and the cement. All types of weird stuff that people are putting in their bodies. I wouldn't suggest it."

"It's actually scary," said Dr. Onyewu. "Honestly, it's scary. It's scary because it's extremely dangerous."

One of his patients traveled all the way to South America for butt implants, but the surgeon there put in breast implants instead.

Baltimore, Atlanta and New York are currently considered hubs for getting the illegal injections. Some have even led to serious illness and death.

Dr. Onyewu said a lot of doctors shy away from dealing with the aftermath of injections, because as he says, reversing these toxic shots is "nothing you can learn in school."

Written by Andrea McCarren, WUSA9