If two girls or two guys are chilling and none is interested in the other, the resulting meeting is that of the "hanging out" and "shooting the breeze" variety. They may talk, play games, or watch movies...all platonic
If a guy wants to "chill" with a girl that he's interested in, whether romantically or sexually she should certainly run in the opposite direction if she wishes to remain single and unattached and is interested in the guy in any shape or form. If she wishes to actually date this guy, she should play extremely hard to get and postpone this "chilling" for as long as possible. Said "chilling" should not occur until the two are actually dating. Prior to this, they should actually go out on dates.
Hey Tiana, we should chill sometime. (red flag if this is from guy to girl)