Lyric discussion by lukefun 

Cover art for Regular John lyrics by Queens of the Stone Age

I think it's about a stalker who becomes obsessed with a prostitute. The line "Your home number's on the wall" suggests she's a call girl and "Where's your daddy now" might point to the broken ome that prostitutes are stereotyped to have grown up in. e wants a relationship with the prostitute and she rejects him painfully. The knife line, I think, is a metaphor for the nastiness in people. The guy's 'knife' is his creepiness, and the girl's is the vindictive way she rejected him.