I don’t like to give a “kinehora..” I don’t say things like “I have never had a broken bone.” I feel that would be to tempt fate.
Kinehora is a yiddush word that means a curse in reverse. It is something to which many people would knock on wood for; or to which an audience would reply, never say never. There is of course, no conclusive scientific proof to verify that if someone makes a remark about, for example as my mother said, never having a broken bone, that all of a sudden they will indeed break one just for cursing themselves. It is a superstition that many people use while going about their everyday lives. My mother describes avoiding saying the curse altogether, while others knock on wood (although many people end up knocking on any surface around them which usually is not wood) to redeem themselves. This avoidance of kinehora is probably one of the most popular superstitions in the US. From my experience, I find educated, wealthy, and even naturally skeptical people not wanting to curse themselves. I find people knocking on wood if they reverse curse themselves or loved ones. It has become a very popular gesture in American culture, and probably worldwide. I know that in England they often say touch wood. Of course, as well, kinehora is a common yiddush saying describing the same superstition.
Regardless of its lack of validity, I think that people find themselves avoiding cursing themselves or touching wood to redeem themselves because it is a little gesture that, if by any stretch of the imagination it does happen to prevent the terrible from happening, is worth little effort that is required to be set forth. It is just one of those things that if it helps people get through their day, then all the power to them.