Jack Osbourne Keeps It PURE

4/30/2007 3:18 PM PDT BY TMZ STAFF
Jack Osbourne partied like a rock star's son for two straight nights at PURE nightclub at Caesars Palace in Vegas.

Arriving around midnight on Saturday, the no longer big O posed for photos with fans and the Pussycat Dolls -- the Vegas burlesque branch, not the "singing" group! Jack then retreated to the club's VIP area with "American Idol" wannabeen Justin Guarini.