doing whatever one pleases; selfishness; self-indulgence
子供に好き勝手にさせるべきではない。
You shouldn't let children do whatever they want.
好き勝手に振る舞うな。
Don't act however you please.
若い頃は好き勝手に暮らしていたが今は落ち着いた。
I lived as I pleased when I was young, but I've settled down now.