a man/woman who uses the internet dating sites to disguise their true identity, whether it be married, in a relationship, who lies habitually for the benefit of procuring sex under the guise of exclusivity; a player, a liar
a married man posing as a single man; a woman living with a significant spouse posing as single; a man/woman telling tall tales to obtain sex under the guise of a monogomous relationship
Akin to the Hoodie Rat, the Avenue Rat is any person (most typically females) who parade up and down a college's "frat row" and/or main college street in constant search of a party.
They are often lushes and are not too far removed from being a skank or man-whore.
"Wow, Jim, check out all the Avenue Rats coming down University Avenue!"
"You know that skank, Karaline? She's such an Avenue Rat. I see her on this street almost every week!"