It's kind of like Global Warming but instead of greenhouse gasses destroying the atmosphere, a lapdog destroys the sense of coldness in your lap

When you have an uncontrollable love of both food and sex to the point where you are left with no choice to combine your passions.
This leads to the logical choice of putting a hotdog up the anus of your chosen partner, but in the interest of not wanting to waste food, proceeding to eat said hotdog afterwards; at this point it has become a warm dog