My kid sister's class sang this on the last day of school when they finished 6th grade (12 years old). It was rather odd. I think there were quite a few parents who were a bit uneasy with that song choice.
One fourth of The XX (the guy who does almost all of their electronic production) took an old knife song, pitched it down and threw some new bits in it. I wish he wouldn't get sued for releasing a properly edited, full length song. This was ripped from a live DJ set of his.