Demi hung with Nick and Joe, her boyfriend Wilmer Valderrama and some other friends on the VIP bus, which looked hella cool with neon blue lighting.
Demi snagged video of the guys getting totally hyped, singing and dancing to Blink-182's "All the Small Things." She captioned it: "Truly a beautiful moment displaying the bond between two brothers.... @joejonas @nickjonas"
In one pic of Demi and Wilmer snuggled up, she captioned it: "Bae photo cred:@joejonas." So cute.
You can also see Demi, Wilmer and Joe leaving the party bus, with Demi sharing: "Rolled up to our party blaring the thong song. Not even kidding."
We're guessing Joe knew the words better to that than he did to Demi's "Confident," which he was captured totally flubbing while she performed at the American Music Awards.
Nice try, Joe.
In other Jonas-related AMAs news, Nick came off quite the hero, saving singer Carrie Underwood from being crushed by one of those giant balls that made the rounds during the show.
He explained: "We almost lost one of the good ones last night at the AMAs. During Coldplays performance these giant light up balls were thrown in the audience. The one in my hands was heroically snatched out of the air by yours truly just before it had the chance to hit the lovely Carrie Underwood in the head. You're welcome Carrie. You're welcome world. #longlivecarrie #countrymusiclives #urwelcome"