cools is the word used when young, Japanese girls refuse to refer to one person. "cools" can be a signal that the girl you are talking to wants to talk to you, but wants you to initiate conversation first. It can also be used when a conversation is dying, and is a signal that the girl in question wishes to continue said conversation. Henceforth, be very careful when proceeding.
"Hey do you see my new bike?"
"Yeah, its awesome!"
"Yeah, i got it for my birthday."