One who attends or attended the University of Texas (t.u.) in Austin, Texas.
The term tea-sip (also spelled teasip, t-sip, or t sip) was started by students of Texas A&M University (aka. Aggies) in the early 1900's to belittle the well-to-do students of t.u.
The University of Texas was traditionally the "rich" school which pumped out doctors, lawyers and the like. A&M was the blue collar school which traditionally taught Agriculture and Mechanics (engineering).