Derek Hough: Halloween Party After DWTS Practice

Derek Hough slips into the back of a car for the 2013 Casamigos Halloween Party on Friday night (October 25) in Beverly Hills, Calif.

The 28-year-old pro dancer attended the bash with younger sister, Julianne, who dressed up as Crazy Eyes from the hit show Orange is the New Black.

PHOTOS: Check out the latest pics of Julianne Hough

Earlier in the day, Derek hit up the dance studio for practice with partner Amber Riley.

“OMG our group dance is INSANE LOL prepare yourselves #teamFoxingAwesome,” Amber tweeted about their team dance for week number eight. Can’t wait to see!

15+ pics inside of Amber, Derek and Julianne…