The Big Girls Don't Cry hitmaker joined Jack Harlow onstage following his performance of First Class, which samples her 2007 track Glamorous. Fergie wore a silver sequin dress with the words "First Class" stamped in red on the front. The moment proved to be a huge hit with fans of both stars, with the likes of Taylor Swift spotted dancing in the audience. Despite the success of First Class, Jack revealed in an interview with Extra in April that he hadn't heard from Fergie about the song.