Teenagers are getting up at 5am to strip supermarket shelves of an energy drink created by two YouTubers.
PRIME Hydration was launched by social media influencers KSI and Logan Paul, and bottles have been selling out in minutes across Asda stores in the UK.
Shoppers have reported "madness in the aisles" as youths scramble to get hold of the £2 sports drinks as soon as new stocks arrive.
Fans have been getting up before sunrise to queue outside shops before they've even opened.
Some outlets have had to limit each customer to three bottles.
It comes as footage emerged on TikTok of youngsters storming an Asda in Bournemouth, Dorset, on Sunday to get their hands on the beverage.
The video shows excited teens charging into the Castlepoint Superstore and scavenging through shelves.
One Asda employee said: “On Sunday we finally had a fresh delivery and there were about thirty kids outside before we had opened.
“At 9.30am we had a member of security outside trying to keep it all under control. As soon as the doors opened they sprinted for the energy drink aisle.
“It was chaos, they cleared the shelves within minutes and were pushing and shoving each other to get their hands on some.”
One disappointed customer said: “I was really looking forward to getting some PRIME, I was looking forward to it all day. I'll keep trying to get some.”
A spokesman for Asda added: “Prime is available in all of our larger superstores and we are pleased that customers are enjoying it.
“We know how popular this product is and we would like to assure customers that our stores are regularly receiving stock.”
British entertainer KSI told an episode of podcast The Fellas in August that the product is only supposed to be available in the UK at Asda supermarkets and Arsenal FC's Emirates Stadium.
But such is the demand that a "black market" has sprung up.
The 29-year-old, from Watford, Hampshire, said: “It’s always sold out man. Honestly, people are selling it on the black market.
“I sh*t you not, the only place you’re meant to get PRIME is Asda and Arsenal stadium.
"But people are getting it at petrol stations!
“Asda employees aren’t even f*****g putting it on the shelves anymore. They’re shipping it out lowkey. They’re like ‘what’s the point, I put it on the shelf and it’s gone instantly. F**k it, I’m just going to sell it on the black market myself.'”
He added: “That’s what they’re doing bro, and then people are making p’s from it because you can’t get it anywhere! It’s not like we’re not supplying enough, we’re supplying loads!”
The drink was banned from schools in the UK due to students selling it themselves.
In response, KSI - real name Olajide Olayinka Williams "JJ" Olatunji - offered schools an entire "truckload" of PRIME for pupils who weren't allowed it.
Flavours of PRIME include Meta Moon, Ice Pop, Blue Raspberry, Orange, Tropical Punch, Lemon Lime and Grape.
Its website said: "Prime Hydration was developed to fill the void where great taste meets function. With bold, thirst-quenching flavours to help you refresh, replenish, and refuel, Prime is the perfect boost for any endeavour.
"We’re confident you’ll love it as much as we do."
It launched in the US in January and finally arrived in the UK in June.