Lesbians. Seen in novel Path of Daggers, Robert Jordan.
Quote from memory:
It's none of my business that you two spend so much time together, for all I know you could be pillow friends.
Unmarried people who do things in bed together
Gosh, I wish she would be pillow friends with me, not just friends
From Robert Jordan's Wheel of Time fantasy series. Used when referring to young novices or Accepted (in training to become Aes Sedai) who are very close friends. Does not neccessarily have a sexual connotation, but refers to young women who share a room or a bed talking late at night about their goals, dreams, experiences: i.e. slumber party.
While pillow-friends as Accepted, Moiraine and Siuan
plan to put mice in Elaida's bed, but they are caught and switched.
A pillowfriend is someone who is super awesome. Different from calling someone your best friend, but similar at the same time. The name was created after "Pillow Talk", a creation for long distance lovers. Of course, the "friend" part of pillowfriend takes the idea and turns it into something for internet friends. Pillowfriends are wonderful, amazing, and simply care about each other so much that all they wish to do is comfort and cuddle the other pillowfriend. They would purchase the "Pillow Talk" wristbands in order to hear each others heartbeat at night while they sleep, and it would enable both people to hear their pillowfriends heartbeat.
Person 1: Hey, did you hear about that new Pillow Talk product?
Person 2: Yeah, it sounds cool. I'm thinking about getting it for me and my pillowfriend.