Simplify the following text for a Grade 15 native English-speaking person.
Original: Kim Thayil befriended ex-Dead Kennedys vocalist Jello Biafra , former Nirvana bassist Krist Novoselic and drummer Gina Mainwal for one show , performing as the No WTO Combo during the WTO ministerial conference in Seattle on December 1 , 1999 .
Simplified: Thayil joined forces with former Dead Kennedys singer Jello Biafra and former Nirvana bassist Krist Novoselic and drummer Gina Mainwal for one show , performing as The No WTO Combo during the WTO ministerial conference in Seattle on December 1 , 1999 .