The Chinese term "打酱油 (dǎ jiàng yóu)" literally means "to buy soy sauce". "打" is a verb here, meaning "to buy or to get" and "酱油" is a kind of liquid flavoring made from soybean. Now it figuratively means "something is none of one's business and one will not bother to make any comments on it".
“打酱油（dǎ jiàng yóu）”的字面意思为“去买酱油”。打：动词，意为“买”，“领取”，用于表示特定商品的购买活动； 酱油：一种由大豆为主原料制造的液态油类调味品。而现在，由于网络的流行，“打酱油”被赋予了新的意思，用于表达某事与自己无关，自己不做评论。
hái zǐ dà le，huì dǎ jiàng yóu le
The child is old enough to buy some soy sauce by himself. He is old enough to take care of it himself.
bú guān wǒ de shì ，wǒ shì lái dǎ jiàng yóu de
It’s none of my business, I am just a passer-by.
The expression was coined by Chinese netizens. The story can be traced back to 2008, when a man in Guangzhou was asked by a journalist from Guangdong TV on the street to give his opinion on the sex scandal involving Hong Kong star Edison Chen (陈冠希，chén guàn xī). Unwilling to make any comments, the man answered, "It is none of my business. I am just a passer-by out to get some soy sauce." After watching the video, the netizens thought the man had avoided the sensitive topic wittily by using the expression "打酱油". Since then, the slang term has been widely adopted by netizens to avoid talking about touchy issues.
"打酱油" , an expression mostly used online is informal and shouldn't be used in daily communication, for it is beyond the understanding of those who are not netizens. It is often used for fun mostly on online bulletin boards or online forums.