Access to the backend. Vulnerability. You can scrutinize every private detail of the open source of joy without being watched. S/he must twist to decipher the intention of your movements. A gift-like action by the reciever demonstrating trust. Knowing s/he is safe. A sexual position incorrectly attributed exclusively to dogs by those nasty Christians who needed to colonize non-white people thereby ruining perfectly good sex lives and other ancient practices.