"He used to hangout with Rick in his dorm room everyday. I sent the tape there, Rick would just throw them in a corner in a box with a bunch of other tapes. Ad would go through the box when he had nothing to do," the rapper continued about how Ad-Rock discovered LL Cool J and convinced Rubin to give him a listen.
LL Cool J said he was then invited to meet with Rubin and started recording with them. Ad-Rock help produced LL Cool J's first song, "I Need a Beat."
The 52-year-old also detailed his Instagram game, the #Furious5Challenge, which challenges contestants to find a certain item in their house within five seconds.
LL Cool J gave Fallon five seconds to find a dog chew toy and something from his daughters Winnie and Franny. Fallon made it back in time with the items and challenged LL Cool J to find the last pair of sneakers he wore.
Ad-Rock and Mike D of the Beastie Boys appeared on The Tonight Show in April where they detailed how the iconic group was formed and how they fell in love with hip-hop.