Celebs K-pop superstars BTS prepped for their Gillette shows at Planet Fitness in Downtown Crossing, apparently Jeon Jung-kook, a.k.a. Jung Kook, a.k.a. HYBE_BIGHIT MUSICAccording to Forbes Korea, the K-pop super group BTS — which spent the last two nights delighting fans at sold-out Gillette Stadium shows — has earned more than Taylor Swift this year. Advertisement:The unannounced visit caused a stir among Boston Planet Fitness members, in particular those who are BTS fans and who did not pick that particular time to work out. “I’ll show you around any Planet Fitness you want!”