The best Cardi B moments co-hosting 'The Tonight Show'

Rap superstar Cardi B joined The Tonight Show Starring Jimmy Fallon on Monday, not just as a performer but as co-host. The “Money Bag” singer quickly picked up the finer points of hosting. She did bits with Fallon during the monologue, and most importantly for any host, she engaged the guest, John Mulaney.

She also engaged with the audience. One lucky fan — who happened to be wearing a Cardi B sweatshirt — was brought onstage. She left an outgoing voice message on his phone, though she forgot to ask for the name and number of the person calling.

Cardi also finally explained the meanings behind some of her signature sounds. There’s “Eeeeooowwww,” which is “… like a sad cat sound. Like a cat that’s going through pain.” Then there’s “Eeeeooowwww!” (higher). “It’s like, ‘Oh my god, I’m hosting the Jimmy Fallon show. Eeeeooowwww!’” And of course there’s “Okuuuuuuurt,” which is ”… like a cold pigeon in New York City.”

Before closing the show with a performance, Cardi and Fallon played Box of Lies. Fallon asked Cardi, “What is in your box?” Cardi answered, “Not a penis.” Cardi was definitely not lying about that.

The Tonight Show starring Jimmy Fallon airs weeknights at 11:35 on NBC. Watch clips and full episodes of The Tonight Show for free on Yahoo View.

Watch Cardi B leave Jimmy Fallon befuddled with her trilling:

Read more from Yahoo Entertainment:

Tell us what you think! Hit us up on Twitter, Facebook, or Instagram — or leave your comments below. And check out our host, Kylie Mar, on Twitter, Facebook, or Instagram.