<P> Knocking on wood--in Britain and Australia the phrase is touch wood--is an apotropaic tradition of literally touching, tapping, or knocking on wood, or merely stating that one is doing or intending to do so, in order to avoid "tempting fate" after making a favourable observation, a boast, or declaration concerning one's own death or other unfavorable situation beyond one's control . </P> <P> Only the spoken party (a singular person) is to actually "knock on wood" at a time . </P> <P> The origin of the custom may be in German folklore, wherein supernatural beings are thought to live in trees, and can be invoked for protection . </P> <Ul> <Li> In Indonesia, when someone is saying bad things, the one that hears it would knock on wood (or other suitable surface) and knock on their forehead while saying "amit - amit". </Li> <Li> In Malaysia, when someone is saying bad things, the one that hears it would knock on wood (or other suitable surface) and knock on their forehead while saying "choi" or "tak cun tak cun" </Li> <Li> In Italy, "tocca ferro" (touch iron) is used, especially after seeing an undertaker or something related to death . </Li> <Li> In Iran, "Bezanam be Tachte بزنم به تخته" (knock on wood)--when one says something good about something or somebody, he or she might knock on wood and say "bezan - am be takhteh, cheshm nakhoreh" ((I) am knocking on wood to prevent he / she / it from being jinxed). The evil eye and the concept of being jinxed are common phobias and superstitious beliefs in Iranian culture, and Iranians traditionally believe knocking on wood wards off evil spirits . </Li> <Li> In Egypt, "Emsek El Khashab إمسك الخشب" ("hold the wood") is said when mentioning either good luck one has had in the past or hopes one has for the future . When referring to past good luck the expression is usually used in hopes of the good thing continuing to occur via its spoken acknowledgment, as well as preventing envy . </Li> <Li> In old English folklore, "knocking on wood" also referred to when people spoke of secrets--they went into the isolated woods to talk privately and "knocked" on the trees when they were talking to hide their communication from evil spirits who would be unable to hear when they knocked . Another version holds that the act of knocking was to perk up the spirits to make them work in the requester's favor . Yet another version holds that a sect of Monks who wore large wooden crosses around their necks would tap or "knock" on them to ward away evil . </Li> <Li> In Romania, there is also a superstition that one can avoid bad things aforementioned by literally knocking on wood ("a bate în lemn"). Wood tables are exempted . One of the possible reasons could be that there is a monastery practice to call people to pray by playing / knocking the simantron . </Li> <Li> In Bulgaria the superstition of "knock on wood" (чукам на дърво) is reserved for protection against the evil, and is not typically used for attracting good luck . Usually people engage in the practice in reaction to bad news, actual or merely imagined . In most cases the nearest wooden object is used (in some areas, however, tables are exempt); if there are no such objects within immediate reach, a common tongue - in - cheek practice is to knock on one's head . Knocking on wood is often followed by lightly pulling one's earlobe with the same hand . Common phrases to accompany the ritual are "God guard us" (Бог да ни пази) and "May the Devil not hear" (Да не чуе Дяволът). </Li> <Li> In Bosnia and Herzegovina, Croatia and Serbia there is also the habit of knocking on wood when saying something positive or affirmative about someone or something and not wanting that to change . Frequently the movement of knocking on nearby wood is followed by "Da pokucam u drvo" (да куцнем у дрво) (I will knock on wood), or sometimes by "Da ne ureknem" (да не урекнем) (I don't want to jinx it). </Li> <Li> In Poland, as well as in Russia, there is a habit of knocking on (unpainted) wood (which may be preceded by saying odpukać w niemalowane drewno or simply odpukać, literally meaning to knock on unpainted wood) when saying something negative - to prevent it from happening - or, more rarely, something positive - in order not to "spoil it". In Czech Republic, this is often accompanied for stronger effect by knocking on one's teeth, a piece of building stone, or metal, reasoning that these (as opposed to wood) survive even fire . </Li> <Li> In Turkey, when someone hears about a bad experience someone else had, he / she may gently pull one earlobe, and knock on a wood twice, which means "God save me from that thing ." </Li> <Li> In the United States in the eighteenth century, men used to knock on the wood stock of their muzzle - loading rifles to settle the black powder charge, ensuring the weapon would fire cleanly . </Li> <Li> In Spain "tocar madera" (literally: to touch wood) is something that you say when you want your luck or a good situation to continue . Ha ido bien toda la semana y, toco madera, seguirá bien el fin de semana . (It's been fine all week and, touch wood, it'll stay fine for the weekend). </Li> <Li> In Latin America, it is also tradition to physically knock a wooden object . A variant requires that the object does not have legs ("tocar madera sin patas"), which rules out chairs, tables and beds . </Li> <Li> In Brazil, "bater na madeira" (hit the wood) is something actually done physically, three knocks are required after giving an example of a bad thing eventually happening . No verbalization is required, just the three knocks on the closest piece or object of wood . In the absence of wood, someone can say "bate na madeira", to prevent the bad thing to happen . People do not actually believe knocking three times a piece of wood will really protect them, but it is a social habit and it is polite to do so to demonstrate that ones doesn't want that bad thing they are talking about to actually happen . </Li> <Li> In Greece the saying "χτύπα ξύλο" (literally: Knock wood) is said when hearing someone say something negative in order to prevent it from happening . </Li> <Li> In Lebanon and Syria the saying "دقّ عالخشب" (literally: Knock on the wood) is said when hearing someone say something negative in order to prevent it from happening . It is also largely observed when saying something positive or affirmative about someone or something and not wanting that to change . </Li> <Li> In Israel the saying "בלי עין הרע" (literally: without the evil eye) is said when someone mentions good things happening to themself or someone else, or even when mentioning a valuable things they own . This expression is a superstition that is used in the hope that a good thing will continue to occur even after it's mentioned, and as a way to prevent Envy (Hasad "حسد") also known as the Evil Eye (Ain Hara'a "عين"), as they believe that Envy can harm other people . </Li> </Ul>

Where did the superstition saying knock on wood come from