Ian came to the clinic complaining he felt pain in every body part when he touched it. Lisa Cuddy quickly figured out he had a broken finger and was perceiving the pain as coming from the body part he touched rather than his finger. Because she was concerned that Gregory House was acting too nicely to people lately, she decided to test him as she knew how enraged House got when he was assigned stupid clinic patients.
Ian saw Dr. House and demonstrated how when he touched anything, it hurt. Dr. House too figured out what was wrong and grabbed Ian's finger, sending him into intense pain and makign it clear to him what was wrong with him. However, Dr. House quickly set the finger and applied a finger splint. Ian felt much better right away.
After a few minutes, Dr. Cuddy became suspicious and asked the duty nurse what Dr. House had done to the "idiot patient". However, at that moment, the newly repaired Ian came out of the examination room with a perfectly executed splint. He said "thanks dude!" to Dr. House, who smiled back at him. Dr. Cuddy realized that depite the patient's stupidity, House was probably kind and patient with him, which got her worried about House's mental state.
It later turned out that she was right. House was on methadone.