I believe I brought this up somewhere around DDF before. Leave it for @TimT to find.
Read this and then decide. I was unaware for most of my life, until someone made me aware. (similar issue with "touch wood")
im just saying that your halachos from 770 and other people in the world are very ymmv
Should prob change the name of this thread - Is it ok to say or write, 'keep your fingers crossed'. As this whole page is elaborating on it..
You need to change your setting to see more messages per page.