Omikuji are fortunes written on thin strips of paper. They are sold at temples and shrines. Japanese people will usually buy one on New Year's Day to see what kind of fortune they will have for the year. Omikuji fortunes range from good to bad in six to seven levels.
It used to be custom that you would tie a bad Omikuji on a branch in the shrine to make it go away, but lately that interferes with the tree growing properly, so it is not recommended.