Sheldon developed diarrhea while participating in a Civil War battle re-enactment. He and his brother George went to the clinic, still in Confederate uniform (with Sheldon dressed as a General) and were seen by Gregory House. Sheldon insisted on staying in character, and House took the opportunity to make fun of their uniforms. Sheldon got angry and went to leave, but George insisted he needed treatment. House got them a sample of anti-diarrhea medication and even offered to make it more "authentic" to the 1860s by adding mercury. George thanked Dr. House and left.
However, George was soon back in the clinic. His hands had become numb while shooting his rifle, causing him to drop it and having the blank cartridge discharge into his foot. He needed treatment of the burns, but suffered no serious injury. He apologized for the fact Sheldon had kept in character.
However, George and Sheldon were soon back in the clinic, vomiting violently. Dr. House took a closer look at their uniforms and realized they were cheap polyester, which is treated with antimony. They likely absorbed it into their skin resulting in heavy metal poisoning. The brothers started arguing about Sheldon's cheapness and House left them to sort it out.