Karissa and Kristina Shannon's 21st Birthday Bash

Making for quite the reason to celebrate, twin sisters Karissa and Kristina Shannon rang in their shared 21st birthday with a booze-fueled party in New York City on Friday night (October 1).

The Playboy beauties - who turned 21 at midnight - first went to dinner at Via De Mille restaurant in SoHo before heading to their very own party at Greenhouse nightclub.

Definitely not a PG affair, Kristina was going wild as she danced around barefoot while drinking straight from the bottle alongside her sis.

Meanwhile, Karissa looked delighted as she unwrapped a gift from her boyfriend Sam Jones III - as her man doted her with a pair of Christian Louboutins which cost a cool $1495.

The party comes just after Karissa hit headlines for sex tape reasons - as she recently negotiated a deal to sell her X rated home video to be distributed by Vivid Entertainment.

Enjoy the pictures of the Shannon twins celebrating their 21st birthdays (October 2).