"Trans-Joi" is a term used in the adult industry to describe a specific type of content that features transsexual or transgender individuals engaging in sexual activity. The word "trans" refers to the transsexual or transgender aspect of the content, and "joi" is a play on words with the Japanese term "jois", meaning pleasure or enjoyment. So, Trans-Joi essentially refers to transsexual/transgender pleasure or enjoyment within adult videos. This tag indicates that the video contains sexual scenes involving individuals who are transsexual or transgender, and aims to provide pleasure and enjoyment for the viewers.