In her autobiography Girl in a Band, Kim says the song is about Joe Cole. A friend of theirs who was murdered during a robbery in Venice, Los Angeles in front of his friend and roomate Henry Rollins.

She says:

When Henry called to tell me about Joe. I burst into tears. I didn’t get over it for a couple of years, to be honest. The senseless, random act of violence against someone so full of life and innocence, was mind-blowing, and I hated Los Angeles for a long time after that. I wrote the song “JC” about Joe, while Thurston wrote “100%”. It was hard to sing without tearing up.