Oooooooooops! Close call!! :o
Now, if that had been me, I'd have pulled the USB connection, gibbered a bit, crossed my fingers whilst praying to the god of fried circuit boards, then plugged it in again.........
Then I'd cry, bin the board, which with my luck would be giving a good impression of a fine Cuban cigar, and get drunk.
The next morning, whilst desperately searching the internet for a hangover cure, I'd undoubtedly order up a new Arduino board. Some people never learn - although I have ordered a second hand copy of Kelley and Pohl's Book on C, so maybe I might be able to disprove the theory of old dogs and new tricks.....although I doubt it :