Harry Styles crashes bachelorette party
- Photo: HarryStyles/Instagram1 of 11
- Photo: O_Albanos/Splash News2 of 11
- Photo: Steve Granitz/WireImage3 of 11
- Photo: Lester Cohen/WireImage4 of 11
- Photo: CKAA/ZDS/WENN5 of 11
- Photo: DDAA/ZOB/ Daniel Deme/WENN6 of 11
- Photo: Kevin Mazur/WireImage7 of 11
- Photo: Invision/AP8 of 11
- Photo: DDAA/ZOB/Daniel Deme/WENN9 of 11
- Photo: LTA/WENN10 of 11
Singer Harry Styles refused to stick with tradition and crashed his model ex Cara Delevingne's sister's bachelorette bash in London on Saturday night, Nov. 30.
Poppy Delevingne threw a wild retro-themed party at the U.K. capital's posh Groucho Club, which was attended by her supermodel sister and famous female friends including actresses Sienna Miller and Jaime Winstone and TV presenter Alexa Chung.
RELATED: 2013's biggest breakups so far
Styles, who was once linked to Cara, did not want to miss out on the fun. He turned up to the bash, which was in celebration of Poppy's final days as a single woman ahead of her wedding to James Cook.
The One Direction star donned a blond wig to impersonate a member of 1990s band Hanson, along with radio star Nick Grimshaw and a female pal.
RELATED: Celebs without makeup
The trio partied at the club until the early hours of Sunday morning, when Styles left the venue wearing a huge elephant mask.
He later posted a photo of himself posing with Miller on his Instagram: "I was part of Hanson."
RELATED: Most expensive weddings
Meanwhile, supermodel Cara had an embarrassing end to the night. She gave a woman driver a shock by hopping into the backseat of her car after mistaking it for a taxi cab.
Fergie, Sarah Jessica Parker, and Heidi Klum all get an F on this week's Fashion Offenders.Watch Video »
Diva Double Date
Beyonce and Alicia Keys double date with their famous hubbies on today's Celebs Gone Social.Watch Video »
Where Are They?
See what the cast of "American Beauty" is up to today.Watch Video »
J.Lo's Mini Me
Prince Harry, Jessica Alba and more stars who threw out the first pitch at baseball games.Watch Video »