Sex Slave: A male or female that assumes a subordinate manner/position and preforms sexual acts for the "Dominant" male or female partner. Can tie into the practice of D/s where the person can do these acts freely or become collared i.e "owned". This role can be voluntary or forced in some situations. Could be considered a Pet.
"Dude, your girl is wearing a collar. is she like your sex slave or somethin?"
"Yes she is my sex slave, why? You want to borrow her?"
"Hell yea, but won't she mind?"
"No, she's collared, she'll do what I tell her to."