Lovely Idiom 殺出程咬金

Chinese idiom：“半bàn 路lù 殺shā 出chū 一yí 個ge 程chéng 咬yăo 金jīn”，it means there is an unexpected person burst out in the middle way AND obstruct the process of plan.

1. 半bàn 路lù ：in the middle way.

2. 程chéng 咬yăo 金jīn : In Chinese history, this guy was a person often took a knife and appeared in the middle way, tried to involve something; due to he acted rashly, people unexpect to see him in any serious occasions. Here is a metaphor of unexpected person and imply this guy impede the plan.

3. 殺shā 出chū :burst out appearing; suddenly coming, abruptly coming, unexpectedly coming…
Here we say 殺出instead of 出chū 現xiàn ，just want to emphasize this guy took a weapon(seems threat or kill) and appear(出現)or come(出來)

Ex:
妳的作業寫完了嗎?
Have you finished your homework yet?
還沒有!
Not yet.
為什麼?
Why?
因為半路殺出一個程咬金。
Because there was a 程咬金came here (and interrupted me).