There's a reason ponies don't practice un-magic much, mostly because it's a lot like regular magic except more dangerous and less predictable. But for some ponies, un-magic is worth the price.

Humble Pie is one of those ponies.

Too bad the price seems to be blowing up Twilight Sparkle's castle at the behest of a voice on a radio.

To re-iterate: there's a reason ponies don't practice un-magic much.