An OCDer would think like this:
SecondYou: There is someone watching you from the dark !
You: Oh shut up:
SecondYou: Ok I will but , if something brakes in an cuts your throat , YOU HAVE BEEN WARNED !
You: FFS SHUT UP !
SecondYou: Think about it: How come ghost stories are all over the TV these days ? What if it was true ?
You: Damn you Secondme ! You know and I know THERE ARE NO ghosts , SHUT UP NOW !
SecondYou: Fine , Fine. But knife crime is up these days and if I were you I'd check outside...
You:
The best way to overcome your obsessional behaviour is to face your fears so tonight after sunset , sit in the bushes and CONFRONT your SecondYou.
HTH.