A last-minute message on Twitter, Internet or Facebook can bring hundreds, even thousands of teenagers out to a designated venue within hours to see their "vlogging" video blogging idols in the flesh.
Teenager Leena waited in line in Paris last month to see France's number two YouTube comic, known as Norman. "I feel like crying," she gushed. "I've seen every one of his videos!"
"It's going to be weird seeing him live," said 13-year-old Eugenie, who has already attended several YouTube Meetups, as the encounters are known.
'Meetups' may have started as low-key bids to boost a YouTuber's reputation, but in many places including Britain and the US they have morphed into professionally organised, commercially driven events showcasing these new power brokers.
As elsewhere, France's "Generation Z" kids born after 1995 whose world is dominated by digital props have quickly embraced the trend.
"Tomorrow I'll be at FNAC Saint-Lazare in Paris to sign autographs. Everyone come!" read a message from 27-year-old Norman full name Norman Thauvaud posted on Facebook, the Generation Z bible, citing a well-known book, CD and electronic equipment store in the capital.
His "Mister Average" persona delivers short posts on teen topics like dating, family or swearing that score eight to 12 million views. He has 5.6 million subscribers and when he announces an event even with just 24 hours notice hundreds of fans turn out.
Eleonore, 16, said she "heard about it on Twitter, thanks to friends."
"We were really excited," said Gary and Mikael, 13-year-olds who also showed up. "It's cool to meet the guy you're following."
Didn't realise my importance
YouTube's own staggering statistics have helped catapult vloggers like Norman to cult status.
The site has more than one billion users and 300 hours of videos are uploaded every minute, according to its press site.
Mobile devices like the smartphones carried non-stop by Generation Z account for half of YouTube's global views.
Yet the transition from virtual to live can be jarring.
Marie Lopez, 19, alias "Enjoy-Phoenix", France's number-one beauty advice vlogger 1.3 million subscribers toured some 15 French cities last year to "meet" her public, mainly girls between 13 and 20.
"I didn't quite realise how important I was for my followers," Enjoy-Phoenix said in a sober follow-up video. "Having 800 people running after you, like that, I was really scared.
"I make videos in my room, I am not Shakira, I have no Oscar. I didn't deserve all this attention," she said.
Fans, too, post numerous videos on the Meetup experience.
Some even record "how-to" guides on handling this "live" encounter. In one, a sassy girl urges fellow "digital natives" to try it, it's real life "and if you don't know what that is, google it first."
Norman organised his Meetup last month to promote a show he will be giving in a Paris theatre.
He is among only a handful of YouTube comics in France who manage to make a living from their craft, thanks to ads that pay one euro ($1.1) for every 1,000 views. YouTube takes a share of the profits.
The 70-odd videos he posted since he started in 2011 have been viewed 638 million times.
'Hitting the jackpot'
And this is a drop in the ocean compared to mega stars like PewDiePie, 25-year-old Swedish video game commentator Felix Arvid Ulf Kjellberg. He has the world's most subscribed YouTube channel more than 34 million and is said to be one of the highest paid YouTubers. Forbes and the Wall Street Journal last June said he took about $4 million in ad sales, "most of it pure profit".
With that much influence, Youtube's Meetups were bound to go bigtime.
"Initially, these Meetups were more impromptu and not well organised," said Thomas Owadenko, co-founder of Octoly, the leading brand management software firm for YouTube which has identified popular beauty bloggers who are then paid for talking about a product.
Today, the Meetups include slick gatherings like VidCon in the US. Now in its sixth year, the next one in July will gather 300 YouTubers for three days in Anaheim, California. It will restrict admittance to 20,000 fans all paying $100 to $150 a ticket.
Similar events are held in Britain, dubbed Summer in the City, and Germany, where it's called Video Days. M6, a French music video television channel, will get in on the act this summer with a gathering called Video City Paris.
"Like many in Generation Z, YouTubers don't expect to live off their videos or to make money, when they start out," said Eric Delcroix, an expert on social networks. "It's like hitting the jackpot."