"When I saw him I was like, 'Got to work on the goals!' I said [to him] I wanna hit that and I ain't talk about drugs," she joked.
Haddish recalled that DiCaprio thought she was kidding. However, she really wanted to have sex with him, but only on one weird condition: if he stayed in his character from "What's Eating Gilbert Grape."
"He was like, 'What? Why?'" Haddish said. "And I was like, 'Well, I like my men a little weak, but also I feel like you did an amazing job, I think you did an excellent performance and I feel like you deserve an award, and here it is," she said, gesturing to herself.
"I don't know if he thought I was playing, but I was dead serious," Haddish said, then stared into the camera. "Call. Me."
After showing a little preview of Haddish prepping to entertain MTV viewers, Kimmel -- who has hosted two Oscars ceremonies -- asked if any stars in audience should be worried about getting roasted by her.
"Nobody should be concerned about being made fun of, because I'm giving all love through my jokes," she said. "But they will be funny."
Since Haddish is such a rising star, mingling with the likes of DiCaprio and Beyonce, Kimmel asked what kind of celebrity digits she has in her phone.
"Well, I don't have every famous person's telephone number, but I got a lot of my favorites," Haddish explained. The "Last O.G." star listed off some celebs in her phone, such as Jada Pinkett Smith, Taylor Swift, Diddy, and Michael B. Jordan -- who doesn't know she has his number.
Watch Haddish host the The MTV Movie & TV Awards when they air Monday, June 18th on MTV.