Henry's Baby Brother was a clinic patient in the Season 1 episode Mob Rules. He's the much younger brother of Henry.
Henry brings his brother in because he's been crying constantly and he thinks he's really sick. However, House figures that Henry, who is alone with his brother, has been ignoring him instead of watching him. He examines the baby and finds a small toy up his left nostril. He removes it with a pair of forceps.
Henry and his brother return a few hours later. The baby has put something else up his nose. House removes another toy. He's still crying and Henry and House can't get him to stop. However, Bill Arnello finds House in the clinic (he's there to talk about his brother's case) and tells the baby he will hurt him if he doesn't stop crying. The baby stops and Bill tells them that the trick is to make the baby think you really mean it.
However, Henry and his brother are back soon after. The baby is crying, but House uses Bill's trick to get him to stop. House finds another toy shoved up the baby's nose and removes it. He thinks the baby is stupid and Henry is neglectful but he notices that the three toys he removed, a fireman, a policeman, and a fire truck, all have something in common. He thinks of something. Instead of getting forceps, he grabs a powerful electromagnet and puts it in the baby's nostril. Another toy pops out - a cat. House surmises that the baby was trying to communicate to them through his choice of toys and is smarter than he first appeared.