Billy Callahan is a life-loving Irishman who comes to Sacred Heart Hospital after being innjured in a bar fight and teaches Turk and J.D. a lesson about living life to its fullest. Meanwhile, Carla and Elliot attempt to make social plans with each other but can't seem to stick with them, which creates tension between the two friends. Elsewhere, Dr. Cox gets a vasectomy behind Jordan's back and is stunned by her reaction when she discovers the truth.

J.D.'S efforts to make a good impression on a first date reach desperate levels when he and Kylie get caught in a hospital quarantine. A series of unfortunate events bring J.D. And Kylie to Sacred Heart on their first date, where J.D. accidentally initiates a SARS quarantine and is forced to resort to desperate measures to make a good impression. While the hospital is in lockdown, the rest of the staff recounts various first date stories leading to the revelation that Dr. Cox and Carla dated in the past.