James Corden has already had major stars like Mariah Carey and Jennifer Hudson singing carpool karaoke, and now he's got Justin Bieber joining in on the fun.

Bieber appeared on Corden's "The Late Late Show" Wednesday night and as the two sat down in the car together, Corden immediately threw on Bieber's 2010 hit song "Baby" and revealed that he's pumped and gets really, really into it. 

The two sang and dance to Bieber's music and at one point, Bieber even rolled down the window to shout "I love you" to a possible Belieber.

Corden jokingly admitted, "I've got to be honest, when I picked you up just now, I didn't recognize you for a minute because you had a top on."

The late night host started questioning the singer on his famous Calvin Klein ad, asking if he received any free underwear for the shoot.

"They sent me a lot of Calvin Kleins," Bieber said. "Like boxes and boxes."

He then went on to confess that he was given too many pairs of underwear to even wear them more than once. "I definitely don't wear 'em twice," he admitted. "There's too many."

"Are you serious?" Corden replied. "You wear a pair of underpants once and then you throw it out? That's the life. I have to turn mine inside out and wear 'em again."

Following the underwear conversation, Corden figured it'd be an appropriate time to ask Bieber if he's ever listened to his music while making love. Bieber blushes and laughs, admitting that he does not, and Corden seemed really disappointed.

The two even switched outfits at one point while discussing what "swag" really means. 

Bieber then sang a Boys II Men song and showed off his awesome Rubik's Cube skills.

Watch the full clip below!