A Chinese tradition everywhere outside of China, fortune cookies are to the non-discriminating restaurant-goer what a free toothbrush is for the everyday dentist's patient: a little extra something at no extra cost. Which certainly is good fortune.
Essentially they are nothing more than a stale biscuit inside which resides a small slip of paper upon which is, ostensibly, the answer to life's great mysteries. They contain words of hope, such as 'A great opportunity will come your way', or of wisdom 'As a dog returns to its vomit, so does a fool return to folly', and of faith 'You think you've got it bad?'.
None of it is terribly enlightening, nor do the fortunes ever come true, which leads many people to think that they got the wrong cookie by mistake. But surely that would mean fate itself made a gaffe, which would deny the whole principle of predicting the future, which would annul any value of the fortune cookie in the first place.
It is best not to think about it too hard.