An apology for a big-time screw-up (from the Latin "mea culpa" for "my fault"). You would not issue a "mega culpa" for eating the last doughnut in the employee lounge, but for offenses such as, but not limited to, robbing a bank, knocking up your sister-in-law, being expelled from school for running an opium den in the boiler room, etc.
"Did you hear Michael Vick's mega culpa after he pleaded guilty to bankrolling that dogfighting operation?"
by Lord Zoltar August 27, 2007