Welcome KCFan2014! And welcome back Karma!
Thanks for the 'touch wood' and 'knock on wood' phrases.

We in the Czech republic has something similar, we say that we 'knock it' (literally translated), in a sentence it is 'I have to knock it' and we knock on a table, or even a wall. I don't use it tho and for many years I thought that people who in tge middle of a conversion start to knock are insane.
