"Never laugh at live dragons." J.R.R. Tolkien, from The Hobbit.
This is a version of Shakespeare's famous 'Discretion is the better part of valor." It's not a good idea to dare forces that are stronger than you are - especially if those forces don't have anything holding them back. In other words, don't play chicken with a universe that doesn't have your best interests at heart. Don't dance in front of the onrushing train; you might get caught on the tracks. I use this wise and hilarious line when it's better to be quiet than confrontational.