Princess Celestia invites the leaders of the other kingdoms to the Grand Galloping Gala, thinking it will make things more interesting. She’s right.
 
Dragon Lord Ember learns a lot about pony parties. She learns that ponies have a very different definition of what constitutes as ‘formal’. She wasn’t even sure what formal party wear meant. Parties can’t be formal, can they? At least Princess Celestia seemed to like her improvised outfit.  
Ember also learns ponies don’t do mock-sacrifices, incorporate fighting techniques into their dancing or scarf down as much food as they can in the shortest possible time. Apparently ponies who are enjoying themselves don’t climb things, screech, or whip burning objects in circles above their heads either. Ember figures it’s because they wear flammable clothes that restrict movement, but she doesn’t understand why they would dress like that if they plan on having a good time.  
She makes a mental note to show Spike what a mosh pit is.