Maybe because it's a thrill for her. Maybe it's some kind of declaration that makes her feel committed to being a slave for her master. I dunno, I'll let her answer that one!Originally Posted by BDSM_Tourguide
I'm guessing she's probably proud of her servitude and awed by the control her master has over her, and wants the world at large to know she belongs to him.
I don't know that it's the safest thing, but it's certainly a sweet act of devotion.