You can describe the specific style of doing something as your mode. If you're in vacation mode, for example, it might mean you say everything in a super-relaxed voice and spend all of your classes daydreaming.
From the Latin modus or "manner," it has been popular since the 1400s. Since the 1600s, people have been using it as another word for "fashionable." The French term "a la mode" literally means "in the fashion," or "fashionable," but is more commonly used to describe as specific way of serving dessert (ice cream on the side).