T-posing is the act of standing with your feet together and your arms spread apart, parallel to the ground and perpendicular to your body. [Memes can be found here.]
Its first noted widespread use was at Georgia Tech Term 1 2018 thanks to a group of vocal students. It quickly gained popularity and notoriety, even among RC's, thanks to RC Hayes who was known to engage in Dominance Battles with TIPsters and other RC's.
Note: please append with other amusing tidbits
At Davidson Term 1 2018, a group of students trapped a few other students in a T-Pose circle at the first dance. The T-Posers circled around the other students attempting to teleport them to another dimension. They failed.