That's it, the last straw! Discord is done with this! He has had it with these mother-bucking ponies and their mother-bucking harmony! After a particularly bad day of not being allowed to be himself, Discord does what he does best. He finds a loophole and exploits the tartarus out of it. Best of all, he'll get to do whatever he wants, guilt trips from a certain yellow pegasus not included.
Then again, telling nopony one's plans certainly has its perks.
And what is his brilliant plan? He's taking a nap. If that nap just so happens to induce nightmares in those he dislikes and mass insomnia in the others... well, no plan is perfect. Dreams are more chaotic than the waking world anyway.
Story takes place in the undefined time between episodes "Keep Calm and Flutter On" and "Magical Mystery Cure".