JLS have promised to "cause carnage" for Marvin Humes' stag party, kicking off proceedings in style by handcuffing him to a dwarf.
The Everybody In Love singer is set to tie the knot to The Saturdays star Rochelle Wiseman later this year and the lads have arrived in Sin City for a mammoth party tour of Las Vegas and Miami to celebrate Marvin's final days of freedom.
JLS tweeted a picture of Marvin, wearing a t-shirt with a picture of a woman's torso in a sexy negligee on the front, handcuffed to a dwarf in the foyer of their hotel.
In a video posted online, the band are seen laughing as the dwarf - wearing a white suit, sunglasses and heavy gold chains - walked up and attached himself to Marvin, telling him: "You do as I say!"
JLS - who were pictured at the airport wearing matching t-shirts with Miami Vegas 05.2012 printed on the back - tweeted: "Uh oh... Vegas!"
Bandmate Aston Merrygold, 24, said: "You heard of the Hangover and Hangover 2? What we are planning will be Hangover 3."
Meanwhile, bride-to-be Rochelle, 23, is at home cooking for her future in-laws.
She tweeted: "Cooking a meal for my Mum tonight and my in laws, a bit of pressure as Pappa Humes is a Chef! Will report back, wish me luck."
Marvin and Rochelle have been dating on-and-off since March 2010, splitting briefly at the beginning of last year.