All actions are coded as being Girl Actions or Boy Actions. Performing Girl Actions will fill up your Girl Meter, seen in the upper left corner of your HUD. Fill up your Girl Meter, and you'll be able to activate Chaos Control
Be careful, though. Boy Actions, in turn, fill up your Boy Meter. Fill up your Boy Meter, and you will enter Hypermode, sacrificing one energy tank to temporarily activate the deadly Hyper Beam.