To be
energetic in a happy and friendly way. Also used to describe relatively small, friendly, enthusiastic
mammary glands found in the human female. E.g.: "She has nice perky
breasts". Past a certain age, male interest in "perky"
breasts takes on a shabby flavor of
dirty-old-manism; when the day comes that your daughter's got 'em, you'd best have grown out of it. Really.