The story behind this is:

Rainbow Dash was explaining something to Twilight, but all of a sudden, she just passed out, on Dash’s shoulder XD

Applejack is lecturing Pinkie n’ Fluttershy for giving Twilight the “sleeping beauty-pills”, Pinkie thought it was a good idea since her friend needs some sleep, Fluttershy got the same idea, but AJ said “Bad girls, BAD girls, no more fun with the sleeping pills and Twi!” Meanwhile, Rarity is having the time of her life filming the moment behind a bush XD