Cavallari Hits 21 and the Bottle in Sin City

She's been seen at 21+ clubs before -- but now "Laguna Beach" hottie Kristin Cavallari doesn't need a fake ID -- she can finally get her party on -- legally!
Kristin Cavallari
TMZ, and our friends at SpyOnVegas, was at Kristin's 21st birthday bash at LAX in Las Vegas this weekend, where she pulled a Lohan and was tossing back champagne from the bottle while dancing around the VIP section.