A term used to describe someone who is slutty or promiscuous, or someone who has had more than the average number of sexual partners.
She's as used as a public toilet.
Just like a Chain Smoker
, someone who lights up one cigarette straight after the other. In this case someone who dates one person after the other. These relation-ships rarely last longer than a month. Normally Chain Daters hang around together and Chain Date each other- a common occurrence in high schools.
John has had 3 girlfriends in the past month, who also dated John's friends, they're such Chain Daters.