I got a call at 12:30 one night a few months back. Apparently some back-end scripts I edited to fix an automated test setup crashed around 75 test pc's and halted somewhere around 2000 tests. I quickly jumped on, fixed the issue, and got everything back online.

I was up all night certain I would get fired. First thing in the morning the client says welcome to the club some, of the best have done the same thing.