So you've rolled a one: that EPIC THING you were planning?
It's not happenning.
But you asked the DM if you still met the DC. The answer was 'no' but, wait, what's that? Now the DM's consulting random tables! Dice are being rolled. As they hit the table each clatter is more sinister than the last.
You can see the damage and random effects mounting before your eyes. Why? Why did you have to push your luck? Now the DM's still rolling dice. If only you could have just accepted a 'no' and moved on before they started rolling on the random tables!
Fortunately, now you can just accept a 'No.' and move on with game.*
*Dice not an actual defense against the DM's wrath.