Meaning:

打包票 (dǎ bāo piào) to be sure or to guarantee

Usage:

“打包票”字面意义是写保证的单据。当对事情有绝对把握，非常确定时人们常说“打包票”。

“打包票” literally means writing a guaranty. People usually say “打包票” when they are very sure about something.

Examples:

1. 我不敢打包票能赢得奖杯，但是我们一定会尽全力比赛的。

    Wǒ bùgǎn dǎ bāo piào néng yíngdé jiǎngbēi, dànshì wǒmen yídìng huì jìn quánlì bǐsài de.

    I can never guarantee we will win the Cup, but we will do our best to play the game.

2. 他拍着胸口打包票，说一定能帮我们订到最好的旅馆。

    Tā pāi zhe xiōngkǒu dǎ bāo piào, shuō yídìng néng bāng wǒmen dìngdào zuìhǎo de lǚguǎn

    Clapping on his chest, he guaranteed that he can reserve the best hotel for us.