"Trans-jerk" is a term used to describe a specific type of porn content. The term is a combination of two words: 'trans' which typically refers to transgender, and 'jerk' which in this context, implies masturbation or self-pleasuring activities.
So, "Trans-jerk" generally means a scene or video involving transgender individuals engaging in self-pleasuring or masturbatory activities. It is targeted towards adult audiences who have an interest in such content featuring transsexual and transgender performers.