Foreshadowing is a warning or indication of a future event. Wayne Campbell from the movie Wayne's World had a dream one night. An Indian came into his home and led him to a desert to meet Jim Morrison to tell him about what Wayne will be doing in the future. He told him that he will put on a concert with his best friend in their hometown of Aurora, Illinois
This is When Bilbo Meets Gollum and Challenges him to riddles. If Bilbo can't get the riddle correct, Gollum will eat him.