Meaning:

回马枪 (huímǎqiāng) back thrust

Usage:

“回马枪”是指回过头来给别人的突然袭击，让人感觉很意外。口语中常说“杀（一个）回马枪”。

“回马枪”means giving somebody a surprise attack which was unexpected. It often say“杀（一个）回马枪”in spoken language.

Examples:

1. 妈妈杀了个回马枪，把小明的游戏机拿走了。

    Māma shāle gè huímǎqiāng,bǎ Xiǎo Míng de yóuxìjī názŏule

    Mother suddenly was back and took Xiao Ming’s recreational machines away.

2. 本来以为他已经走了，结果他杀了个回马枪，弄得我措手不及。

    Běnlái yĭwéi tā yĭjīng zǒule, jiéguǒ tā shāle geè huímǎqiāng,nòngde wǒ cuòshǒubùjí

    I was unprepared when he gave me a surprise return as I thought he had gone.