It's the British equivilent of saying knock on wood.

Contrary to popular belief it has no relation to touching men's wood.

However it is most commonly said in order to prevent a confident statement from bringing bad luck.

Meaning to hope for the best.

When said most people will touch or knock on wood and some strange people will also knock on their heads!

n. The birth name of somebody who has changed their name. Most commonly attributed to trans people, but can be attributed to any person who has changed their name. (sometimes written as two words: dead name)

v. 1. To call somebody by their deadname.
v. 2. To out somebody's deadname to the public.

To avoid bad luck

cockney slang for draw blood