In 1924, Dr D X Bible, the head coach of the Longhorns was "braced" & "backed into a corner" by the Dallas Morning News & the Houston Post about WHAT "the football boys" were drinking out of coffee cups after the A&M game, in the locker room (it was PROHIBITION & the players were also mostly UNDERAGE).
(note: it was said to have been straight CORN LIKKER, brought in by an alumni!)
Dr Bible said, "WHY they're drinking TEA of course. University of Texas students are NOT crude like those UNsophisticated, hayseed, AGGIES across the way."
UT fans/players have been called "teasippers" ever since.