On day three you receive a radio call to go to a murder scene at building 621, apartment 5 (A. Hapsburg).
There's no murder, only a confused old woman (and her dog) with a shopping list for some donuts.
Run over to the donut shop and when asked the quantity of the order, the correct selection should be the first option each time - 2 donuts, 4 donuts (apple and something jelly) and 6 sesame. Take the donuts back to the woman. She'll deny ordering them and encourage you to eat them.
Eat the donuts at the first prompt, then again at the second. When you come to the third prompt - the sesame donuts - select the option to feed them to the dog, who is also named sesame. You'll find out why...