The Price of TEA in China!

TTTTT - Urgent Update. 5ts have been infiltrated. The 5t organization has used the UT System as a cover for their own poserhood for so long, that the query "U T?" has not been answered in the negative since Memorial Day. A clever conspiracy theorist devised a cunning plan that has devastated the entire U5T establishment! The AGGIES have a joke that makes a true Texan an AGGIE! You seem surprised? This can't have happened? YOU SAY THAT NOW!
Back in the days before 5ts, the Roman "Orange Julius" became Caesar. Being a creative military bastard, he used a number between 0 and 26 for a password to make a variety of substitution ciphers available to his men. If the password was 5, then an "T" became a "Y," and an "O" became a "T." If the password was 12, the letters changed such that a "T" became an "F," and an "H" became a "T." Over the years this cipher was understood better and better, until finally it needed a name. Rather than call it "Alphabet Soup," which was taken early in the evolution of encryption, they lit on "Caesar Shift." Shift to present day Texas. A legit 5t was sitting in a sparsely attended cinema theater, preparing to watch "Valkyrie," when out of the darkness came the quiet query: "U T?" Upon an affirmative answer, the voice began the traditional hand shake: "Did you hear about the Aggie... that thought his password couldn't be guessed?" This new form of call and response alerted the otherwise eligible 5t all unsuspecting. "No," he said. "It was Caesar -SHIFT-" she said, and was gone. Aware of the potential urgency of the situation, the 5t made his way to the nearest branch of the UT system library, to access the 5t archives. 18 hours had passed, and this is the optimum window of opportunity to respond - too quick to seem apathetic, but leisurely enough to avoid the appearance of desperation. His finger quickly turned the pages of the Dewey decimal computer catalog. C-a-e-s... he suddenly understood. The SHIFT in question was not spelled out, but rather intended to be used in tandem with the letters themselves. In absence of a familiar "T" the 5t was puzzled in the extreme! Which letter could he possibly be expected to capitalize upon? I'll leave you to experimentation, only with this warning: So many non-Aggies have mastered the related mathematical concept of permutations that the original Aggie in question may NEVER be identified (whether telepathically or otherwise!) This is so serious that it may even effect a change in China - to the price of Tea!