>>222241
Since the thread is so old and it was created after a story in Upstairs explaining the origin of the term "washers" I will tell you without any beating around the bush.
Pic related are washers and in this context it's a euphemism for female breast areola.
This is a thread dedicated to IA's nipples, or more precisely, the pigmented area on the breast around the nipple.
It's a small part of the larger movement (which doesn't exist) called: "Free the Vocaloid nipple!"
The twist to all this is that you will find very few images displaying IA's exposed nipples here. Basically, you're getting teased THE FUCK OUT in a soft-core lewd thread.