“But … there was ooze all over the place. And one of the guests threatened to send somepony to another dimension!”
“I know. Can you imagine how dull it would have been if I hadn’t invited Discord?”
Celestia’s hatred for the Grand Galloping Gala is the best. It seems that after that fiasco from the first season, she decided that hey, I can actually enjoy the gala if like that.
This less than holy sense of humor is one of the reasons I love Celestia so much. Yeah, letting Discord out had a strategic purpose, but I’ve been waiting for “I have a use for his powers” to start showing up in this context.
And poor Twilight is still so caught up in her own orders and schedules and planning that even as she’s known Celestia for years, she didn’t see this coming.