Pena said that Rousey wasn't graceful when her team lost and that she was constantly running her mouth.
At the end of the last episode of "TUF 18," Rousey flipped the bird at Miesha Tate after a fighter from the star judoka's team lost.
Tate was simply trying to shake Rousey's hand and show some class after the win, but Rousey raised some eyebrows by pointing her middle finger in her rival's direction.
"I think that was just the cameras. I didn't see that," Pena said of the incident between Rousey and Tate. "But I had known that Ronda was saying things to her, Ronda being like, ‘You smiling at my girl's pain is another reason why I'm gonna f--king destroy you.' Like, I saw that, so I'd known that she was running her mouth and constantly saying stuff. But I didn't know she'd flipped her off.
"You know, what do you say to somebody who's like that? I like her spirit, I like her attitude. They don't like to lose. Nobody likes to lose. That's cool that she's very ‘about' her team. On the flip side, I feel like it's classless to act so -- what's the word? -- like, with such big bravado. The girl is like, ‘I'm the f--king s--t, so I can't lose.' She doesn't know how to lose gracefully, and that's okay because she's the champion and there's a reason for that. I like her style. However, I don't think it would've killed her to be a little more professional."
Pena also hinted that Team Rousey assistant coach Marina Shafir told her it would look bad for her in the media that she's on Tate's team.
"I got, like, ambushed by a drunk (Team Rousey assistant coach) Marina (Shafir), telling me that if I didn't choose a better side, that when the show comes out, everything in my life was going to be a lot more terrible, media-wise. Basically she was threatening me," Pena said.
"No she didn't want me to choose Team Rousey. She was just basically saying, like, ‘know where your loyalty is at.' That type of deal. Meaning, because I'm on Miesha's team, if I continue to be on Miesha's team, it's going to be bad for me, media-wise. Like I'm going to get ripped apart or something. I don't know. She was being drunk and weird, and I was like, whatever, you don't know me. It was crazy."