I'm not a superstitious person and it surprised me when I met my OH's friends and family (who are German) to realise that Germans seem to be superstitious people. I guess I thought they'd be too rational for all of that. For instance, opening birthday presents before your birthday or celebrating before the day is considered bad luck.
Another one they are mad about it when you say cheers and clink glasses you must look into the eyes of the other person or you'll have seven years of bad sex. Funny when my missus is staring someone down and they don't know why

So, people of AH, do you have any superstitions or have you heard of any weird ones?