The porn video tag "cock-growth" refers to a specific fetish or fantasy involving the visual and narrative emphasis on the growth, expansion, or enlargement of a male's genitalia (specifically the penis), often exaggerated for heightened effect. This can be represented through various techniques such as time-lapse photography, animation, or CGI effects to create an illusion of the penis growing in size and/or thickness during sexual activity or stimulation. The tag suggests that the content is intended to arouse viewers who have a particular interest or fetish for this specific aspect of male sexuality.