Lady Gaga Joins Semi Precious Weapons Onstage At Lollapalooza

'It was pretty amazing,' frontman Justin Tranter tells MTV News of Gaga jumping on drums.

CHICAGO — In the hours before Lady Gaga’s Friday night (August 6) set to close out the first night of Lollapalooza in Chicago’s Grant Park, the ubiquitous, world-conquering pop star made an early appearance onstage as part of the set by Semi Precious Weapons (her friends and the opening act on her Monster Ball Tour).

Semi Precious Weapons frontman Justin Tranter breathlessly recounted the story while standing just in front of the stage where Gaga would be performing her full set in a matter of hours.

“She came to watch us perform. She stood on the side of the stage, and then during the song ‘Magnetic Baby,’ she started playing drums with Dan,” he told MTV News. “Then she started singing backup vocals, then her and I made out, and then she stagedove and then I joined her while she stage-dove. And then we made out while stagediving. And then she left. It was pretty amazing.”

The visit certainly came as a surprise to the men of Semi Precious Weapons, though it isn’t the first time the two entities have tag-teamed. “She used to get onstage with us all the time, but since she’s so famous, normally it’s not safe for her,” Tranter explained. “But she played the same stage we played three years ago, and I think she was so excited about us playing that stage, and she loves our band so much that she was overwhelmed by the rock and roll and just had to make it happen.”

Tranter also told MTV News that this wouldn’t be the last you would see of Gaga collaborating with the band. “Gaga herself has plans to collaborate with us, both artistically and sexually,” he teased.

After a whirlwind day, Semi Precious Weapons declared themselves the victors of Lollapalooza’s Friday.

“Tonight, in 2010, at Lollapalooza, rock and roll officially is back,” Tranter said. “After Gaga is done, between our set and her set, they should just cancel the whole thing.”

Are you looking forward to a collaboration between Gaga and SPW? Tell us in the comments!

Lollapalooza 2010 is happening now — make sure to check out MTV News’ Lollapalooza Live, streaming Saturday and Sunday at 5 p.m., right here on MTV.com. And follow all of Lollapalooza on the MTV Newsroom blog.