As a twisted figment of Riley's encounter with clowns, Jangles is a giant clown with blue hair, a white face with a creepy smile, a large red nose, and bright green eyes. He is dressed in a red top and blue polka-dot pants with big floppy shoes and carries a huge mallet.
In real life, Jangles was an entertainer who attended 6 years of drama school prior to his job. When he was hired for Riley's third birthday party, Riley became so scared of him that he traumatized her. The experience created a gigantic, twisted version of him within Riley's mind and was kept in Subconscious.
When Bing Bong is put into Subconscious, he is imprisoned in a cage made of balloons on top of the slumbering Jangles. After Joy and Sadness rescue him from Jangles, Joy wakes him up to get Riley awake so they can use the Train of Thought to get back to Headquarters. Luring Jangles into Dream Productions, Riley captures his image in her dreams and wakes up. Joy, Sadness, and Bing Bong then hop on the train and escape the rampaging Jangles.
It is unknown what happened to Jangles in Riley's mind, although it can be assumed that Jangles destroyed Dream Productions, and was subsequently locked back into the Subconscious.
During the credits scene, the real Jangles is seen at a birthday party and is revealed to secretly hate his job. His emotions are shown too.
Several Pixar employees confirmed that Jangles is a tribute to their old friend, Joe Ranft, who occasionally dressed up as a clown named Buttocks.
Many of the memory orbs in the real Jangles' mind are blue, purple, or green.
As revealed in the Inside Out themed-You Choose The Ending book, "Forget This!" at the birthday party where Riley met Jangles, he put Riley in a balloon pit whom she could not get out of, and her mother had to come and rescue her.
All of his emotions are men and wear clown make-up.