你玩够了吗？ 我受够了 两个人就够了or两个人就足够了

It's the same with English sentence"It's enough! ". Also, you can repeat it twice like "够了够了" to emphasize the situation, using a polite tone when your friends give you something(food, money, presents...) to explain they are kindness or warmth, using a short/fast tone when you was fed up with something or somebody(it's very unpolite).

If you pour the water to another cup,and it's enough you will say:"這樣夠了，不用再倒了。”