放荡不羁 [- - bù jī]lead a fast [licentious] life; give full rein to one's low passions; have full swing; have one's fling; have [take] one's swing [one's full swing]; licentious in conduct; unconventional and unrestrained：
•¶ 这个孩子自从父亲死后就放荡不羁了。 Since his father's death, the boy has had full swing.