Why do you knock on the table when you say "If i were to die..."?

[nq:1]In one episode of the sitcom Friends, I noticed that everyone knocked on the table when they were saying "If i were to die...". Why is that? Does knocking on the table dispel the bad luck of assuming one's own death?[/nq]
To touch wood is a way of conjuring bad luck out (only if you are of the superstitious kind). Is this superstition unknown in Australia? I have the (slight) idea that i

[nq:2]In one episode of the sitcom Friends, I noticed that ... table dispel the bad luck of assuming one's own death?[/nq]
[nq:1]To touch wood is a way of conjuring bad luck out (only if you are of the superstitious kind). Is this superstition unknown in Australia? I have the (slight) idea that it is of Germaninc origin, as some trees were sacred for the ancient Germans.[/nq]
In AmE, the a

[nq:1]To touch wood is a way of conjuring bad luck out (only if you are of the superstitious kind). I have the (slight) idea that it is of Germaninc origin, as some trees were sacred for the ancient Germans.[/nq]
I've heard it comes from touching the cross.
Michael Hamm
BA scl Math, PBK, NYU

[nq:1]In one episode of the sitcom Friends, I noticed that everyone knocked on the table when they were saying "If i were to die...". Why is that? Does knocking on the table dispel the bad luck of assuming one's own death?[/nq]
No, "knocking on wood" is merely an informal superstitious action signifying "I hope a good fortune sort of event occurs, or that a bad fortune event does not occur".

[nq:2]In one episode of the sitcom Friends, I noticed that ... table dispel the bad luck of assuming one's own death?[/nq]
[nq:1]No, "knocking on wood" is merely an informal superstitious action signifying "I hope a good fortune sort of event occurs, or that a bad fortune event does not occur".[/nq]
In my experience, it's slightly different and more specific, but wouldn't be used in the si

[nq:1]In AmE, the actual phrase is "knock on wood", matching the action DJ describes. I've heard "touch wood" from BrE+ people; do those BrE people also knock on the wood when they "touch wood", or do they sort of gently touch the wood?[/nq]
The action suits the words on both sides of the Pond.

Matti

[nq:2]No, "knocking on wood" is merely an informal superstitious action ... occurs, or that a bad fortune event does not occur".[/nq]
[nq:1]In my experience, it's slightly different and more specific, but wouldn't be used in the situation DJ cites. It's not ... rather ensuring that a good thing that's just been mentioned (either ongoing or expected) doesn't get taken away or negated.[/nq]

[nq:2]In my experience, it's slightly different and more specific, but ... (either ongoing or expected) doesn't get taken away or negated.[/nq]
[nq:1]To touch wood: touch sth made of wood in the belief that one will avert ill luck. So I thought that there were a cultural difference between the Spanish and English use of this superstitious behavior.[/nq]
I suspect that "touching wood" and "

[nq:2]Jinx: person or thing that brings bad luck. It seems ... to ward off is bad luck, not "jinx" as defined.[/nq]
[nq:1]The jinx is the mention of the good fortune. Knocking on wood "cancels" the jinx. The consequence of the jinx ... are apparently not cancellable by knocking on wood. Mentioning that your team's pitcher is currently throwing a no-hitter, for example.[/nq]
A different use

[nq:2]In one episode of the sitcom Friends, I noticed that ... table dispel the bad luck of assuming one's own death?[/nq]
[nq:1]No, "knocking on wood" is merely an informal superstitious action signifying "I hope a good fortune sort of event occurs, or that a bad fortune event does not occur".[/nq]
Well, with reference to immanent death, there's "Knock, knock, knocking on Heaven's door...