A competition one-piece swimsuit with a zipper cleavage cutout that has gone viral from this tweet.
Also known as "Front Zipper One Piece Swimsuit", "One Piece Zip Front Swimwear", "Zipper Front Swimsuit" or "That Competition Swimsuit" in reference to the similar open-chest sweater ("That Turtleneck") phenomenon.
This tag implicates one-piece_swimsuit and meme_attire (learn more).