The phrase "transcumz" appears to be a combination of the words "trans" and "cumz," which is likely a typo for "cums." In this context, it's a porn video tag related to transgender adult content involving cumming or ejaculation. So, it refers to scenes featuring transgender individuals engaging in sexual activities that lead to orgasm and ejaculation. This tag is specifically designed for viewers who are interested in such adult content and want to explore transgender-focused pornography.