Ronda Rousey is not someone you want as your enemy. Justin Bieber made the mistake of dissing her kid sister earlier this year, and the MMA fighter has not forgotten.
Rousey's 16-year-old sister was unimpressed by everyone at the Cannes Film festival -- except Justin Bieber. So Rousey approached Bieber, who was taking pictures with other girls, only to get shot down immediately.
And then her sister uttered the five most heartbreaking words a teen girl can say: "I'm not a Belieber anymore."
It is worth noting that Bieber is bros with Rousey's sworn enemy, Floyd Mayweather, because every celebrity beef has an appetizer.