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?"
The reason Batman can do whatever he wants and is unstoppable. Found kn the famous YouTube HISHE. Basically an excuse to do anything you want, but only if you are Batman, because Batman is the best.
Note: occasionally Batman finds others who also fight over saying “because I’m” or “I’m”. I sampled include:
Yondu “Im Mary Poppins y’all”
Groot “I am Groot”
Thanos “I am inevitable”
Iron Man “and I am Iron Man”
Captain America “I am Steve Rogers”
Captain America “I can do this all day”
Spider-Man “I’m your friendly neighborhood Spider-Man”
Mario “it’s a me, a Mario”