Overall its a justifiable excuse for when you do something completely amazing or really stupid. From passing an exam to accidental setting your house on fire due to the fact that you didn't catch that last flaming chainsaw.
Example 1

Guy 1: "Dude how did you score with mandy last night?"

Guy 2: "Because I'm Batman!!"

Example 2

Officer: "Sir do you know how fast you were going?"

Guy 3: "It doesn't matter how fast I was going because I'm Batman!!!"
by Hourglass Mage May 5, 2011
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