Pinkie Pie gives Fluttershy a new treat for her breakfast, a packet of lime flavoured jelly cubes. However being to hungry to wait for the water to boil, Fluttershy decides to take a quick nibble of her new treat.

The results of eating a packet of lime flavoured jelly cubes while writing.

Jelly = Gelatin for Americans etc. Pinkie mentions it during the story in her own special way.