Katy Perry’s “left shark” lives on.
Over ten years after the “Roar” singer’s shark backup dancer—specifically the one to her left—went viral for its dance moves during the 2015 Super Bowl Halftime Show, Justin Trudeau made a subtle reference to the moment with his Halloween costume amid his and Katy’s burgeoning romance.
For his partner costume with 11-year-old son Hadrien Trudeau—one of three children Justin shares with ex-wife Sophie Grégoire Trudeau—the former Canadian Prime Minister dressed up in an inflatable shark costume, holding aloft a bitten surfboard as Hadrien cowered as a surfer by his dad’s side.
“Ready for Halloween with Hadrien: he’s the surfer, I’m the shark (to his left),” Justin captioned his Oct. 31 post, including a reference to left shark. “We built the costume together —a little father-son Halloween teamwork.”
And indeed, in addition to the photo of Justin and Hadrien posing was one of the 53-year-old—also dad to Xavier Trudeau, 17, Ella-Grace Trudeau, 16—crafting the surfboard from foamboard at his dining room table and one of Hadrien painting it.
But while Justin’s reference to Katy may have been an if-you-know-you-know moment, her fans definitely knew. Soon enough, his comment section was home to a GIF from the 2015 Super Bowl halftime show in question, featuring Left Shark.
Days before Justin’s social media nod to the “Firework” artist, Katy—who is mom to 5-year-old Daisy Dove with ex-fiancé Orlando Bloom—subtly soft launched their relationship on social media, months after the pair first sparked romance rumors with a dinner outing in Montreal.
Within Katy’s Instagram post celebrating her 41st birthday was a video of her blowing the candles out on a cake backstage at one of her Lifetimes Tour concert dates. In the clip, hidden among the dancers and crew members clapping and cheering Katy on was Justin, his smiling face visible for just a moment.
She captioned the Oct. 29 photo carousel, alongside a biting lip and heart emoji, “Level 41.”
But while Justin was swimming in the seas on Halloween, Katy continued her Lifetimes Tour in Europe, with dates in Prague, Czech Republic, and Munich, Germany, on Oct. 30 and 31.
Sharing a glimpse of her time in the first city, Katy captioned a Halloween photo dump on Instagram, “Thank you Prague. I went in your clock and I am filled with your schnitzel.”
To see how more celebrities rang in spooky season, read on.
Paris Hilton
As Tinker Bell, the "Stars Are Blind" singer brought some magic to Vas Morgan, Michael Braun and Raising Cane’s founder Todd Graves' Halloween bash.
Mindy Kaling
The TV star did her best impression of Timothée Chalamet cheering on the New York Knicks.
Kourtney Kardashian & Travis Barker
The Poosh founder and Blink-182 drummer wanted to live like Jack and Sally.
Kris Jenner
The Kardashians star donned a sexy ringmaster look for the big day.
Justin Trudeau & Hadrien Trudeau
The former Canadian Prime Minister and his son had a fintastic partner costume.
Sherri Shepherd
The Sherri host channeled her inner Morticia Addams in this Wednesday-inspired look.
Sheinelle Jones
It's been umpteen Halloweens on The Today Show and Sheinelle has done it again in a Beyoncé-inspired look.
Craig Melvin
Nothing compared 2 the Today co-anchor's homage to Prince.
Lindsay Lohan, Bader Shammas, Luai
The Mean Girls star and her family are ready to save Gotham City with the trio dressing up as Batman.
Gigi Hadid
The model and her daughter Khai—who she shares with ex Zayn Malik—were a monster-fighting duo dressed as characters from Disney's Zombies 4: Dawn of the Vampires.
Mariah Carey, Morocco & Monroe
The family celebrated Halloween in Japan.
Kelly Clarkson
The Kelly Clarkson Show host underwent a film-noir makeover.
Today Show
The entire Today crew embraced the spooky spirit.
Savannah Guthrie & Jenna Bush Hager
Being Miranda Priestly and her real-life counterpart Anna Wintour at the same time? Groundbreaking.
Kelly Ripa & Mark Consuelos
The Live hosts kicked off their Halloween episode with Hamilton-inspired looks.
Al Roker & Carson Daly
The Today Show hosts costumes Rocky III costumes were a total knockout.
Demi Lovato
She's been freed. The "Heart Attack" singer paid homage to her internet meme alter ego, Poot Lovato, for her Halloween costume. As she wrote on Instagram, "been so locked in this era thought i’d let pootvato out."
Leah Kateb
Bow down to the Love Island USA season six finalist's ravishing red ensemble inspired by Princess Jasmine in Aladdin.
Trisha Paytas
Refreshing! The podcaster joined husband Moses Hacmon and influencer Oscar Gracey for a group costume as the Saja Boys from KPop Demon Hunters.
Kourtney Kardashian
The Kardashians star let fans in on her Bride of Frankenstein look.
Tana Mongeau
The LA-based influencer swapped coasts for the night, curling her blonde locks to channel Sex and the City icon Carrie Bradshaw.
James Charles
Complete with smudged red lipstick and costume jewelry, the YouTuber looked terrifying as Gladys from the recent horror hit Weapons.
Andy Cohen & Bette Midler
Iconic as ever, Bette recreated her self-titled 1973 album cover while on the red carpet for her New York Restoration Project Annual Hulaween fundraiser. Andy was also in attendance, donning Andy Warhol's signature black turtleneck and silver locks.
Val Chmerkovskiy & Jenna Johnson
The Dancing With the Stars pros brought their son Rome to trick or treat at the Disney+ Halloween Fest, hosted at The Walt Disney Studios in Burbank, Calif.
Sophia Umansky and Alexia Umansky
RHOBH star Kyle Richards' daughters enjoy Tequila Don Julio signature cocktails at their private Halloween party in Los Angeles.
Ben Platt & Noah Galvin
The couple went all out for Bette Midler’s New York Restoration Project Annual Hulaween fundraiser. Ben dressed as Hugh Hefner while Noah transformed himself into a stunning Playboy Bunny.
Chloe Bailey
“IMA WHOLE LOTTA WOMAN,” the singer-songwriter captioned her all-gold ensemble, emulating Foxy Cleopatra from Austin Powers.
Paris Hilton
Paris paid tribute to a fellow 2000s icon, recreating Britney Spears' latex red body suit from the "Oops!... I Did It Again" music video.
Natalia Bryant
The model flashes a big smile at Universal Studios Hollywood’s Halloween Horror Nights on Oct. 25.
Kim Kardashian, North West & Kris Jenner
The trio proved their internet knowledge, with Kim dressing up as TikTok star Jay Guapo and North dressing as Jay's younger brother, known as Pink Cardigan. Kris also joined in on the fun, dressing as Jay's mom, Chrissy G.