A tight plastic cap is not an attractive option for protective headwear in 30C heat. Yet 22,141 people opted for just that – along with a white shirt, black tie and aviator sunglasses – in Hyde Park, London, on Friday afternoon. It was both a homage to the rapper Pitbull, the night’s headliner at the BST festival, and part of setting a Guinness World Record for the “largest gathering of people wearing bald caps”.

“I’m speechless. Who would have thought a first-generation Cuban would be record-breaking and record-making?” said the rapper, accepting the award in an all-black suit.

Pitbull, a bald man, had to put on a cap to count towards the record himself. According to Will Munford, an official adjudicator for Guinness World Records, it was not a record for the “largest gathering of bald people”, so for Mr Worldwide (the rapper’s nickname) to be counted he had “to wear a bald cap to be in the record number”.

In order to ensure an accurate result, Munford said there were “400 volunteers to individually check people” at the entrance and onsite, and “drone footage with 42 counters backstage”.

Such was the demand for the caps in the lead-up to the gig that many were left scrambling at the last minute. “I went to three different fancy dress shops this week and they were all sold out,” said Lucy, 30, who came with her best friend, Hannah, to see Pitbull for her third time. She had worried they’d “stick out like a sore thumb” if they were “the only people in a sea of bald caps without one. It feels like an inside joke with 60,000 people.”

The idea for the world record attempt did not come from Pitbull, BST or the Guinness World Records. It started with a fan.

“This whole thing is happening because of me,” joked Jack Remmington, a podcast host and cultural commenter. When BST announced Pitbull’s performance last year, Remmington posted a “tongue-in-cheek” TikTok video suggesting that the 65,000-person capacity of BST was “easily enough to break the world record of people cosplaying as Pitbull”. The video went viral and soon Remmington was in contact with Guinness World Records and on BBC Radio 1 with Greg James as they texted Pitbull to ask if he would be up for the challenge. Mr Worldwide gamely replied: “Dale!” (Spanish for “hit it” or “go ahead”, and the title of one of his albums).

The record is “not novelty”, said Munford. The decision to officiate the attempt was made partly because of the sheer number of people involved to make it happen, but also because “a lot of people get to take part in record-breaking that wouldn’t have had the chance to in the past”. It also helped that there was a pre-existing grassroots internet community committed to dressing up like Pitbull.

The trend of Pitbull mimicry started in 2021 with just a few fans showing up as playful lookalikes. Thanks to a few viral videos on social media it quickly exploded into a massive fan movement whereby it is now simply par for the course to show up to Mr Worldwide’s show dressed like him. The Cuban-American rapper has embraced the phenomenon by naming his fans the “baldies” and selling an official Mr Worldwide Kit and bald caps on his website, for £40 and £10 respectively. Both are sold out.

Shawna, in a bald cap, and Jack, who is bald, two 33-year-old friends, aren’t diehard Pitbull fans but came because they thought it would be a nostalgic night of carefree euphoria. “It’s the least pretentious crowd I’ve ever been in at a gig,” said Shawna. “The world is literally burning, so why wouldn’t I stick a bald cap on and dance around to some pop bangers I loved at uni to feel something good?”

As the sun sets and the rapper took the stage, he was visibly taken aback by the number of impersonators screaming every lyric back at him. As he acknowledged the historic moment, he said: “It’s a blessing and an honour to see the baldies in London.”