Superstitions

I suspect chess players aren't really a superstitious lot. All that rational thinking at the board probably extends to real life, leaving little room for the irrational. However I still come across players who have their little 'quirks' which may be considered superstitions by some.
Probably the most common is the 'lucky pen'. Players who start and event with a couple of pins may attribute this to their choice of writing implement, and therefore try and hang on to it for as long as possible. Apparently Tal was a believer in the 'lucky pen' and attributed his World Championship loss to it going missing during the match.
Related to this is the lucky shirt/socks/key ring etc Unlike the lucky pen, if items of clothing are involved, a winning streak may not be so much due to magical forces, as to the smell from wearing the same socks six days in a row.
I've also observed scoresheet superstitions. Not writing an opponents name down until the completion of the game is one attempt at voodoo, while incredibly cheeky players might try and get away with a pre-filled result. Not shaving during a winning streak has been mentioned, although I'm not sure whether I've witnessed this happening at chess Olympiads, or are just mixing with people of poor personal grooming.
Finally, I once had a player who said that one of the best ways to not lose was to avoid players whose surnames started with 'Fischer' or 'Kasparov'