Did a little quick-search and I found this:
source: http://www.phrases.org.uk/meanings/my-bad.htmlShakespeare used the term with something like the current meaning, in his Sonnet 112:
Your love and pity doth the impression fill
Which vulgar scandal stamp'd upon my brow;
For what care I who calls me well or ill,
So you o'er-green my bad, my good allow?
Neat.