Ruffled things are frilly, or edged with fancy ruffles. Your little sister might love her ruffled dress so much that she wants to wear it every day.
A bird's ruffled feathers provide it some protection as well as looking attractive to potential mates. You can also describe things that are mussed or rumpled, by a hand or the wind, for example, as ruffled. Your dog's ruffled fur might be caused by the breeze — or she might have her hackles up because she sees her mortal enemy, the mail carrier. The root of ruffled is probably the Low German ruffelen, "to wrinkle or curl."