Rosabelle believe:

I've been having a bit of a paranormal / ghost themed week over at the Real life is horror tumblr [X] 

and while writing a brief post on Harry Price (the famous supernatural investigator. I'll post it here a little later) I started to read about Harry Houdini and found out this short but interesting story. 

(pic source)

Harry Houdini and his wife, Bess, came up with a secret phrase that they would use to contact one another from the grave if one of them was to die before the other. 

The phrase was “Rosabelle believe”. 

Following the death of Houdini (Halloween night in 1926) , Bess performed annual seances on the anniversary for a decade. 

The code was never relayed to her and she eventually gave up, stating that ten years was enough time to wait for any man.

(pic source left. Pic source right)

Houdini Wikipedia [X]

NPR article [X]

The great Harry Houdini [X]

Magic tricks.com [X]