It's like he's coordinating a ransom drop.
A sad side-effect of online delivery middle-man sites like Seamless is the decline in creative methods for anti-social people to avoid human contact. We can write things like "have an evil day" in the special instructions, but we don't get to peek through our blinds and watch the delivery guy read it for the first time, as the author of this envelope surely did. We really respect the "ring the door bell 3 times" system to make sure he knows who's out there. This misanthrope clearly doesn't want there to be any circumstance in which he has to open that door unless there's pizza waiting on the other side.