Rainbow Dash always thought she knew everything about her little pink friend, but when Pinkie lured her to Sugar Cube Corner with the promise of cake, she was surprised by what Pinkie had to tell her. Before she knew it, Rainbow was at Pinkie's mercy. Pinkie leaned over for a taste of Rainbow's cutie mark and a taste of something else.

The picture is called SURPRISE WING BONER by The Dark Lord Keisha from DeviantArt.