08/09/2010 12:00 pm ET Updated Dec 06, 2017

Lady Gaga Crowd Surfs During Semi Precious Weapons Set At Lollapalooza, Fan LICKS Her Stomach (VIDEO)

Lady Gaga drew a massive crowd for her performance at Lollapalooza in Chicago Friday night, but even before she started her set--she surprised some fans at a smaller stage.

Gaga joined Semi Precious Weapons at the BMI stage Friday afternoon--where she performed in 2007. The band's front man Justin Tranter called Gaga to the stage, and she then jumped into the excited crowd. One excited fan even decided to lick her stomach.

"If anyone calls Lady Gaga a pop star I'll f***king kill them," Tranter told the crowd. "She is a rock star, and she is helping, Semi Precious Weapons, bring rock'n'roll back. Rock'n'roll is back b**ches!"

WATCH Gaga crowd surf here: