The joker is the card that can become anything, so it is read as unpredictability and the trickster within. It can also point to someone whose role in your life is hard to pin down.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.