Machine Gun Kelly's (MGK) recent show in Rosemont, Illinois, on Thursday night, evolved into more than just a concert; it became a heartfelt celebration of friendship. During one of the final dates of his 2025 Lost Americana tour, the audience was treated to a surprise appearance by longtime friend, pop star Halsey. She joined MGK on stage for an electrifying performance of their nine-year-old Billboard Hot 100 hit, “Bad Things.”

Halsey took on Camila Cabello’s original part in the duet, singing iconic lines such as “Am I out of my head? Am I out of my mind?/ If you only knew the bad things I like” and “Don’t think that I can explain it/ What can I say? It’s complicated.” Her unexpected duet with MGK brought an added layer of excitement to the show.

While Halsey was on stage, MGK delivered a poignant speech, honoring her resilience and strength in overcoming numerous health struggles in recent years. He specifically acknowledged her battles with lupus and a rare T-cell lymphoproliferative disorder. “I wanna give flowers to this amazing woman, who’s had a very, very, very tough couple of years,” MGK stated, as Halsey visibly blushed. He added, “Health scares that I got to personally watch her fight through, and I don’t know if we’ve acknowledged that enough, how much you mean to music, and how much you mean to me as a friend.”

In clips captured by fans at the event, MGK further emphasized Halsey’s ongoing battle and dedication. “Seeing you that way during the time, and seeing you now …,” he remarked. “I mean, this girl is still going through chemotherapy and fighting every day, and she’s out here crushing it.” Halsey has been transparent about her health journey, having revealed in 2024 that she was diagnosed with lupus and the T-cell disorder two years prior. Before commencing her own Back to Badlands Tour in October, she underwent another round of chemotherapy, highlighting her commitment to both her health and her career.

The deep bond between MGK and Halsey is well-documented, spanning several years. Their collaborations include the 2020 track “Forget Me Too,” featured on MGK’s ‘Tickets to My Downfall’ album. Halsey also previously made a guest appearance at MGK’s Mainstream Sellout Tour show in Los Angeles in 2022, underscoring their enduring friendship and mutual support within the music industry.