used within the community of a certain affluent southern university, especially in the circles of greek frat life. when a boy is drunk or being creepy and trying to hook up with a girl, he is "trying to chill". this might entail inviting the girl back to his room to "listen to music" or perhaps drink more alcohol. however, this should be immediately interpreted as the boy trying to hook up with the girl.
girl: yeah, he was trying to chill last night even though i told him i had a boyfriend.