Prince William and Kate's Striptease Surprise
04/04/2008 AT 07:15 AM EDT
Middleton – in a pink strapless dress with a pleated skirt and a flower at her waist – kissed her boyfriend of five years as the pair boogied. William twirled her around as the pair danced to Little Richard's "Tutti Frutti" and then to Guns N' Roses' "Welcome to the Jungle."
"They looked happy and so in love," says a guest at the burleque themed-bash. "Kate was smiling so widely and they looked like there was no one else in the world when they were dancing."
The pair – plus Prince Harry, who's just back from his African holiday with Chelsy Davy – were attending an event for The Henry van Straubenzee Memorial Fund. (Henry, a school pal of Harry's, died in a car crash in 2002.)
Princess Beatrice, her boyfriend Dave Clark, and Middleton's sister Pippa also attended the soirée, which included a relatively raunchy hour-long cabaret act.
Both William and Middleton averted their eyes as a stripper performed. At another point, William blushed (and Kate giggled) as a female singer presented the Prince with a rose – putting it between his teeth. (He promptly removed it and stuck it in the ice bucket holding a bottle of vodka.) And the couple sang along enthusiastically during a drag queen's Southern-flavored rendition of "Purple Rain."
The cabaret set covered everything from the "shocking, the unbelievable to the slightly risqué," organizer Marina Fogle, a co-founder of party planners Kasimira, tells PEOPLE. "It was completely different [from] any charity event that anyone had been to before – there was no formality and stuffiness."
William and Middleton skipped the afterparty at favorite royal haunt Mahiki, but Harry and Beatrice partied on, joined by her younger sister Princess Eugenie.
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