I think it is about the Valentines Day massacre, which was (I think) started by Al Compone somewhere in the 50's or 40's. Basicly what happend is that he found out one of his friends (on worker/fellow killer) died, shot and killed. I can't remember all the exact details or names, so look it up, if you want to.
If you do look it up, listen to the words closely and it might make sense. If it don't, don't come and shoot me.