Bad psychology pun...
Two psychologists were out ice-skating. One was a follower of Freud's philosophies, the other was a follower of Carl Jung's. As they were skating, the psychologist who studied Freud hit a bad patch of ice, and his feet went out from under him, and he fell flat on his rear.
His friend just started laughing and laughing, and couldn't stop. Irritated, the man brushed himself off, stood up, and said, "What's so funny?"
The Jungian recovered, took a deep breath, and replied, "Sorry, but that's the first time I've ever actually seen a Freudian slip!"
Hah!