They done a master move to be honest :
By making a nb t-shirt for womens and another one for mens, they knew people would notice and share a screenshot of this, and people that would see the screnshot would share it again, and people that see the screenshot shared by those who seen it would be like "wait ts cant be real lemme check" and they would search up the thing and they see its real and share the link with the screenshot.
People are like WTFFF and they share again, and again, and again, until it becomes so popular that fathers and mothers that got a nb child are like "ohhhh ts would be a nice gift for my child" and they would buy it and boom, sales rates explodes and it goes in trending items bought, making it even more popular.
And at some point one of the daughter of the parents that seen the screenshot shared by the people that seen the shared post of the peoples that seen the post of the one that wondered if it was real because he saw the screenshot that was shared by the people that have seen the screenshot *breath* will probably wear one nb shirt while making a tik tok dance vid that will get viral, this making the shirt even more on trending.
This is how you make mass money.
