According to my handy-dandy ArtScroll Machzor, some Jews refrain from eating nuts during the first ten days of Tishrei. Art Scroll says this is because (a) nuts create excess mucus and saliva which may make it harder to pray correctly; and (b) the gematriah of egoz/nut is chet/sin.
As the brighter bulbs in the audience have already realized, both reasons are false. Nuts do not make us drool and the gematriah of chet and egoz are NOT the same. Anyway, even if the numbers added up (which they don't!) what do we suppose God would do if he saw us eating nuts? Penalize us for sins not commited? Can the ArtScroll authors really worship a God that is so petty, and so unreasonable?