This porn video tag describes a scenario where a male teacher is involved in sexual activity with another male, indicating that the content is of a homosexual nature. The word "gay" is used here to specify the type of same-sex attraction involved. The term "teacher" adds an element of power dynamics or authority figure, which can be a common theme in certain types of porn. It should be noted that this tag assumes the viewer has a basic understanding of what porn videos are and the concept of sexual orientation.