In addition to performing with Chris Brown at JAM’N 94.5 Summer Jam in Boston, Big Sean gave an impromptu performance of his hit “My Last” backstage. But instead of bringing out Breezy, he was joined by singing-rapping duo Karmin. The G.O.O.D. Music MC asked the YouTube phenoms to perform with him, saying he was a fan of their work. Apparently he wasn’t the only one. Lupe Fiasco also rocked with the Boston natives on “The Show Goes On.”

Side note: Karmin’s cover of Nicki Minaj’s “Super Bass” already has over 1.5 million views and an endorsement from Nicki herself. “I am LIVING for this!!!!” tweeted the Young Money rapper.