Image imported from derpibooru 
Original Description:
 
A month and a half has past and Sugar has gained 645 pounds. One day, she was waiting outside Canterlot High School for her boyfriend, Big Mac. As Mac had exited the school, he spots his noticeable girlfriend. Their reunion was shortlived when he also spots a sudden wardrobe malfunction with Sugar’s dress; seeing that her buttocks was nearly exposed as her massive weight was pulling up the bottom of her dress. Embarrassed, Sugar suggests on getting a larger size.
 
Check out Part 1 here.