Hello iobit, I am guessing that it is a reference to a line from this song by the Velvet Underground. Sunday Morning Sunday morning, praise the dawning It's just a restless feeling by my side Early dawning, Sunday morning It's just the wasted years so close behind {Watch out, the world's behind you} There's always someone around you who will call It's nothing at all Sunday morning and I'm falling I've got a feeling I don't want to know Early dawning, Sunday morning It's all the streets you crossed, not so long ago {Watch out, the world's behind you} There's always someone around you who will call It's nothing at all {Watch out, the world's behind you} There's always someone around you who will call It's nothing at all Sunday morning Sunday morning Sunday morning Watch out, "something" is behind you. This is usually a warning to be aware of a danger behind you that you are not able to see. For instance, Watch out, there is a bear behind you! Watch out, the world is behind you. This probably should be understood in a figurative or poetic sense. The problems of the world are always with you even if you can't see them (as if they were behind you.)