The 19-year-old singer was seen heading to London's Groucho Club for friend Poppy Delevingne's hen party on Saturday (30 November) and he certainly embraced the funky fancy dress requirement of the evening.
Along with Radio 1 pal Nick Grimshaw, Harry took inspiration from the well-known American boy band of the 90s, Hanson, and donned a huge curly blonde wig, as well as a backwards cap, a checked shirt and a pair of blue shorts.
He completed his Hanson costume with a pair of red Vans trainers and carried a set of drumsticks, while Nick wrapped a bandana round his eye-catching wig and opted for a pair of ripped denim shorts instead.
The BFFs teamed up with another friend to form the 'MMMBop' trio and partied the night away with famous faces including Sienna Miller, who Harry grabbed for a quick photo.
Harry posted the picture on his Instagram page and wrote: "I have no idea. @sienna."
Last month, the young ladies' man was seen leaving a dinner date in Los Angeles with Kim Kardashian's little sister, Kendall Jenner.
However, despite always appearing to have a new hot girl in his presence, Harry recently confirmed that he is "still available".
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