Funny / Time Lords and Terror

• When The Doctor *ahem* "re-modulates his vocal cords" with Fluttershy to activate the Hervoken Charm Cube. Try to imagine David Tennant speaking in Andrea Libman's "Fluttershy" voice without laughing.
• Pinkie Pie's ability to dumbfound the Doctor is both hilariously in-character and believable.
• The Doctor's reaction to his ponification:
  "I've heard about regenerations going wrong before, but never one that ended in...pony!"
• Pinkie Pie "advertising" the summoning charm for the S'Muz, which caused all the ponies that heard it to completely crack up:
  "Warning: use of summoning charm can cause vertigo, nausea, and may unleash a malevolent cosmic monstrosity upon all reality; do not use under any circumstances," Pinkie Pie said in her best advertising voice.
• Rarity's reaction to the TARDIS.
  Rarity: It's so... tacky!
  The Doctor: What?!
• Twilight's computer is programmed to show a virtual Pinkie Pie whenever it comes up with something that doesn't make sense. Think about that.
  Virtual Pinkie: Nonsense is what sense sees when it looks in the mirror!
  Twilight: Why did I even get this app?