Thank you The_Love_Child for making this gif.
Stashed in: gifs, G4!, Doctor Who, Reaction GIFs!, Redheads, High Quality gifs, Reaction Gifs, @karengillan2, The_Love_Child
She's reacting to a compliment from James Gunn, director of GOTG.
You can watch the video here (around 00:48 mark is where it starts):
Karen Gillan reacts to a compliment: