Article continues below advertisementPrince William and Kate Middleton may have partied a little too hard.According to a new report, the duo caused an "uproar" while celebrating Pippa Middleton's husband James Matthews' 50th birthday on Saturday, September 20.The theme was "racy" (supposedly a nod to the financier's love of Formula One), and the royals were not afraid to get "wild."Article continues below advertisementSource: MEGAKate Middleton and Prince William celebrated James Matthews' birthday.