In The Big Bang Theory (2007) - The Pancake Batter Anomaly (2008) Sheldon mentions going to Germany as a teenager (specifically when Penny asks if he's never been sick alone before). Sheldon tells Penny that he was a visiting Professor at 15 and living in Germany by himself because his mom had to return home. However, this episode indicates he goes for a summer class as a student instead.
According to the TV weather map, Medford is most likely Livingston, Tx., with Lufkin being onward northeast.
Sheldon tells Linkletter and Sturgis that maybe it's time he starts "chasing the caffeine dragon". This is a reference to the drug term "chasing the dragon", which is a form of inhalation originating in the opium dens of the 19th century.