This traditionally refers to a type of exhibitionist competition popular since the 1970s. However, in modern internet culture, it often relates to:
Various "Wet T-Shirt Challenges" where participants douse themselves in water for humor or views.
Often used on platforms like TikTok to refer to a close female friend or a relatable woman.
A standard digital multimedia container format used to store video and audio. Related Cultural Context Ruby Waters - WET T-SHIRT (Official Video)