an admission of guilt and culpability.
latin--both words are in the ablative; syntactically here the "ablative of means"
It's not really "my bad" as much as it is, "this happened because of my problem." it isn't nearly as casual, and significantly more causal.
The Rutgers team is composed of nappy-headed ho's!
Sharpton/various self-serving whistleblowers:
blah blah blah racism
Don Imus: mea culpa, please don't fire me.