坐牢相关表达：
good time
good conduct time
good time credit
means time deducted from an inmate's sentence for good behavior while in prison
表示监狱里面的犯人因为做了一些好的行为而被减刑

do time
在监狱服刑
I did time at the Changsha county jail for robbing the jewelry store.
我之前因为抢劫珠宝店在长沙县监狱关了一阵子。

in the pen
在监狱里（此处pen为penitentiary的缩写形式）
His wife ran away with another man while he was in the pen.
他在监狱的时候，他的老婆和另外一个男人跑了。

其他相关表达：
have a good time
means to have fun
玩得开心、愉快

all in good time
This means that if you be patient, the thing you are waiting for will happen.
慢慢来，别急，该来的总会来的
I really wish that working hard will make my gym become successful.
我真心希望努力能让我的健身房成功起来。
All in good time.
别着急，慢慢来。