Here is how I explained it on Facebook:

"It's a line from the song "Screenager" by Muse. The full lyric is "All the scars on your skin: 'post no bills'." You know how if the owner of a building doesn't want flyers or anything posted on their walls they'll write "post no bills?" Same concept, except it means something more along the lines of "don't cut anymore, stupid!!!" =P"

The person I was explaining it to isn't quite as familiar with Muse as everyone on here.