It didn't!
The first time she hit the button, Will's sentence cut out in mid-run, replaced with what was
actually on the radio, only with Will's voice replacing the lead singer.
The second time, Will's voice was replaced by the singer.
The THIRD time, the song cut out and Will continued talking with "...hey! Don't do that. I'm trying to sa...."
The FOURTH time, it went back to Will's voice over the song.
A toggle!