Vine's six-second-clip superstars turn fame into cash
Q. Who in their right mind would pay teenage boys known for fart jokes and sexist and homophobic slurs to advertise products in blink-and-you-miss-it internet videos?
A. Pepsi, Coke and many other global brands eager to connect with young consumers.
The social media app Vine allows users to easily create and share six-second videos online.
In a short space of time, it's become incredibly popular with teenagers, and its stars - called Viners - are increasingly being paid to promote products to their young followers
But the Viners are mostly teenagers themselves.
And without the benefit of an entourage of publicists, the advertisers are taking a risk associating themselves with uncoached youngsters thrust into the public eye.
"It's a risk that brands have to take now in order to connect with their audiences," says Jeetendr Sehdev, a professor of marketing at the University of Southern California.
He adds that online celebrities are often more popular with young people than movie and TV stars.
The most followed person on Twitter-owned Vine is 16-year-old Nash Grier, who was a North Carolina schoolboy before internet stardom brought him to Hollywood.
More than nine million followers watch and "re-vine" his videos - pillow fights, throwing water on a sleeping friend, cute interactions with his baby sister, lip-synching to pop songs.
It's all fairly standard teenage behaviour... except when it goes wrong.
Grier and his friends were widely criticised for being sexist when they posted a YouTube video about how girls should behave to be attractive - be natural, but have no body hair, they suggested.
And he was blasted for yelling a homophobic slur in one deleted Vine video that resurfaced online last month. He apologised, expressed remorse publicly and begged forgiveness.
In the past you might have expected this to have proven a major career setback.
In fact, his online following increased and there was no suggestion of him being dropped from a forthcoming DreamWorks movie.
"The difference between Nash and other celebrities apologising is that people actually believed him," Prof Sehdev says.
Because online stars are created by their audiences ""likes" and follows, he adds, their fans often feel a strong sense of ownership over them.
Rob Fishman, the co-founder of Niche.co, which connects social media stars with advertisers, says young people are sick of "overproduced Hollywood-style content" and can better relate to the comedians and teens who dominate social media.
"Some can act, dance or sing, but a lot of the teens are chiefly personalities," he says.
"They have connections with their fans, but it's not any specific talent - it's how well they can connect."
But what can you actually say in a six-second video?
It takes a certain amount of comic timing and pacing to be a successful Viner.
Liane Valenzuela - a musician with more than 2.8 million Vine followers, known as Liane V on the platform - says six seconds is more than enough to create an impression.
She started Vine as a hobby, and now it's become a job.
One recent commission was to make a sponsored Vine for Jennifer Lopez's new song, Booty, paid for by the singer's record company.
A friend and fellow Viner filmed Liane and her father dancing outside their North Hollywood home.
The clip was captured on a smartphone, and edited right there on the pavement, allowing them to reshoot parts to get each dance step in time.
"The secret to making a successful Vine is to be funny, obviously," she says.
"It's to create great content that's relatable that is very creative and - you just can't think too much - just enjoy it and have fun."
Viners say their followers don't mind them endorsing or advertising products - as long as they stay authentic and only advertise stuff that they'd use anyway.
Each deal is different, but the ballpark rate most Viners charge is about $1,000 (£594) per 100,000 followers.
At those rates, Nash Grier could earn nearly $90,000 per six-second video - or $15,000 per second.
But it's a fine line keeping your fan base happy with your authentic self and cashing in on company's desire to market to your followers.
Viner Greg Davis Jr says he received nasty comments from fans recently after creating a sponsored clip for Coca-Cola's Share a Coke campaign.
"I got so much hate and backlash and negativity from the Coca-Cola ad. They called me a sell-out," Davis says.
But he adds that he was paid well and would do it again if asked.
More recently he has accepted an all expenses paid trip to Paris to attend a movie premier with fellow Viner DeStorm Power.
The film studio told them they wanted them to Vine and Instagram about the film to encourage their followers to see it.
"When you have millions of people following you, you have a big influence," explains DeStorm.
"So when they have movies coming out and I say, 'See this movie,' those people are probably going to want to see the film."
Vine is itself fairly new - the app celebrated its first birthday in January - and like its stars, will no doubt change as it matures.
But the challenge both the app and its clip creators face is to ensure their audiences keep feeling entertained and not exploited by the ad men.