This porn video tag, "big-ftm-dick," refers to a specific type of content involving a transgender man with a large penis.
"Big" in this context indicates the size of the penis being above average or considered large by those who view it. "Ftm" stands for Female-to-Male, which is a term used to describe a person who was assigned female at birth but now identifies as a man. The combination of these terms suggests that the video contains content featuring a transgender man with an above-average sized penis engaging in sexual activities.
Please note that this tag is designed for adult audiences only, and it should not be used by individuals under the legal age for viewing explicit content in their region.