Chapter 1, when you've unlocked the Post Office.
You need
* Tranquilliser (from the Doctor's office)
* Coupons (from Toni's, you'll need the Tranquilliser, the dart and the funnel to get these)
In the post office, open both the hatches on the right. Use the tranquilliser with the white cat, use the espresso with the orange cat needs Then use the coupons with the postal robot.