Amount of time it takes for a dog to "do its business" is directly proportional to outside temperature + suitability of owner's outerwear.

Framed like a mock “law” of nature, the line humorously describes a familiar pet-owner experience: the colder (or otherwise more uncomfortable) it is outside—and the less prepared the owner is with proper clothing—the longer the dog seems to take to relieve itself. The joke turns on perceived causality and irony: the variables that matter most to the human (temperature and outerwear) appear to influence the dog’s timing, as if the dog were indifferent or even mischievously calibrated to maximize the owner’s discomfort. It’s a small, domestic observation that uses pseudo-scientific language (“directly proportional”) to elevate everyday annoyance into a witty principle.