We all know the saying "What happens in Vegas, stays in Vegas," but not this time around.

Some of music's biggest acts -- including Demi Lovato, The Weeknd and Kanye West -- hit up the iHeart Radio Music Festival in Las Vegas and, being that it is Sin City, we wanted to find out about their craziest, most memorable (or unmemorable, depending on how cloudy their brains may have been) and scandalous nights out on the town.

As expected, some artists wanted to keep mum about their Vegas adventures, while others were happy to spill their secrets. Jason Derulo wasn't shy about winning big -- "I'll be winning $10,000 here and there," he told us -- while Big Sean brings along his lucky charm: his dad.

"I've had times where I brought my dad here and we've been in strip clubs," Big Sean said. "Throwin' a lot of money, have some drinks at the craps table, roulette, all of that."

But some Vegas memories aren't quite as fun. Just ask "Vampire Diaries" star Kat Graham, who got into a huge fight with her BFF.

"We had too much to drink and we were having a fight in one of those long ass cab lines," she said. "And that was right after I fell offstage because I was onstage with Lil Jon and Steve Aoki and I totally fell back and scratched my leg."

Check out the video to get all the details about these crazy Vegas nights.