Inspired by the following greentext from /rgre/
 
>“This sounds like one of Twilight’s friendship lessons.”  
“There’s no reason to deal with mares when I have my right hand.”  
>Discord eyes said appendage. “What if your right hand was a mare?”  
“What?”  
>Discord fixes you with a savage grin, “I know how the lesson will work.”  
>A pregnant pause ensues.  
>Was that line supposed-  
>OH GOD, THE PAIN!  
>Your right arm is wreathed in magenta flame to the elbow.  
>Your left hand clutches the stricken limb as you scream, but there’s no heat against that hand even as your right arm feels like you stuck it into a pool of molten metal.  
>First the flesh, then the bone, melts away under the magical inferno, pooling on the dirt.  
>“Hah,” Discord’s laugh cuts through your screams, “Earth pony.”  
>The blaze fades when nothing remains of your right arm below the elbow.  
>Beside you, on the ground, lies a tiny foal, a filly of no more than a couple years old.  
>“Huh. Not enough material. This lesson might take longer than I thought.”  
“What…”  
>The screaming’s over, but your voice is hoarse. You look up at him, blinking back tears.  
“What have you done?”  
>“You should thank me, Anon; now your right hand can love you back! It is your own flesh and blood, after all.” Discord’s eyes light up. “Oh, that’s an even better lesson! You can learn to deal with mares by raising one! I’ve outsmarted even myself with this one. What comes next? Oh, right, Twilight writes a letter to Celestia. I’d love to chat about your new fatherhood, Anon, but there’s procedure to follow, I hope you understand. Arrivederci!”  
>Just like that, he’s gone, leaving you with…  
>Your own flesh and blood.  
>You’ve seen pony magic prosthetics. This was a bigger issue.  
>She was your daughter.  
>You pick her up with your left hand and pull her close to your chest, doubling over as a surge of phantom pain shoots up your right arm.  
>You didn’t know the first thing about foals.  
>After Twilight helps you with that arm, you’ll need her help with a lot of other things.