According to their Instagram, the #Tatatowel is a patented solution to your boob sweat problems. 

Great for nursing or pregnant -getting ready - lounging - gym - spa. 

So it looks like it's something you put on while doing your hair and makeup instead of a robe to solve the issue of underboob sweat. 

You can buy one at:  www.TaTaTowel.com

They are $45 and come in many different colors. 

It seems like they are a huge hit