A promiscuous woman, or a woman who has game. Usually both. Similar to the word slut, but lacking any more derisive or offensive meaning for a female than the word playa has for a male.
She's got all the guys after her... what a ladyplaya.
A fat frat boy who sits on his ass watching discovery channel programs on tigers and eating massive amounts of Cool Ranch doritos and drink massive amounts of health shakes. He constantly gos on safari and cockblocks the tigers.
A guy who swears that he likes you, but continues to deny it, flirt with other girls, or tell you to your face that he likes " so and so". These people tend to lie about it so much that they engage in passionate arguments with you about it.