Green Day‘s Billie Joe Armstrong, 47, just threw Ariana Grande, 26, some serious shade! The rock star was chatting about 17-year-old Billie Eilish‘s success when he unexpectedly compared the two pop artists. “[Billie and brother Finneas O’Connell‘s] music is very real, and you can tell it all comes from them, which is what sets it apart from what other pop acts are doing,” Armstrong said to USA Today in an interview published on Feb.