With a pairing of these two for my Jinglemas story this year, it took quite the restraint to avoid making the obvious pun in the story*: a pun so obvious, the show put it in a Season 1 episode written before Berry Punch had even been designed as a background pony. Light spoilers below for the story, of course; read at your own discretion.
RAINBOW DASH:"Heh, looking back at this, Twilight, you might say that you needed help learning how to train your dragon!"
TWILIGHT: "Oh, sweet Celestia, reverse my alicornhood and kill me now..."