But there was one artist who could truly call herself the Queen of Lollapalooza, the type of performer who managed to permeate every festival-goer's mind and attitude all day long. Not only did Lady Gaga deliver an unbelievably energetic, passionate, hard-hitting set of her own, but she also dropped in on friends Semi Precious Weapons to bang on the drums, sing backup, make out with singer Justin Tranter and do a full-on stage dive into a sea of humanity.