A way of admitting a mistake, and apologizing for that mistake, without actually apologizing. 表示道歉的方式之一，相当于"my fault", "my mistake", "I apologize"。但实际并不是很重要的事情，并且这些事情也不会有很严重的后果，其实并不是真正的道歉。比如路上两个人不小心撞到了对方，坐地铁时不小心踩到别人等。
We can put it this way. "I did something bad, and I recognize that I did something bad, but there is nothing that can be done for it now, and there is technically no reason to apologize for that error, so let&`&s just assume that I won&`&t do it again, get over it, and move on with our lives."
"My bad" is an American slang that was made popular by basketball players in playground games in the 1970s and 1980s. It was used by young urban players when admitting to an error.
这个俚语源自于七八十年代的美国，开始时流行于街头篮球。球员之间犯规或者小的错误时就会说my bad。后来逐渐被广泛使用，不仅是在美国，在澳大利亚也是常见的英文表达。它比I’m sorry 更加随意。
"Hey, you spilled my Coke all over me!" "Oh. My bad."