go one step too far字面意思多走了一步，引申为做得太过分了。

【例句】
You blamed them like that, you have gone one step too far.
你那样批评他们，你做得太过分了。

I can enjoy a joke as well as the others but this goes one step too far.
我跟别人一样喜欢开玩笑, 但这个玩笑太离谱了。