After his son Biff wins a young businessman contest in school, a cookie company became interested in his son's animal crackers. Abe then asks the player to help him by perfecting Biff's cookies and lending 500 simoleons. (see Lions and Tigers and Bears quest)
The cookie company, Amalgamated Cookies, like the animal cracker samples and asked that they talk about licensing the brand. Abe then asks the player to help ramp up production fast by building an Animal Cookie Factory.
After Biff spends most of his earnings on a Hippo Pond, a Panda Bamboo Park and a Biff Wing at a Zoo, Abe sets up a Unicorn Ranch. Biff gifts the city a Creampuff Factory, to Abe's dimsay because he is lactose-intolerant.
A list of all Abe Sullivan Quests can be found here.