WATCH: Shawn Mendes says he'd pay $500 For Justin Bieber's boxers

Of course, he belted out a few tunes too.

As Shawn Mendes begins his weeklong Late Late Show (US) takeover, he first had to complete the right of passage that is James Corden’s famous Carpool Karaoke.

The teen idol jumped into the passenger seat to chat to the TV host about Ice Hockey, Harry Potter, moving out and in a strange turn of events, Justin Bieber's’ boxers.

In a conversation about how he’s finding life without his parents, the 19-year-old confessed that his mom cleans his house and does his laundry most days.

Corden then lets Mendes in on the fact that Justin Bieber wears a new pair of boxers every day, instead of washing a pair.

The conversation quickly moved to questioning whether his fellow-Canadian singer sells his used boxers and Mendes revealing that if he did, he’d happily buy a pair for $500.

Of course, it wasn't just that, he belted out a few tunes too.