The inverse law is a mathematical formula used to find the number of drinks you need to bring a girls perceived looks up to a level at which you would bone them.
Number Of Drinks Needed = Desired Level (1-10) / Current Level (1 - 10)
Fat girl: Wanna fuck?
Bro: That Girl is like a .6! You cant do it.
You: Well i'll bone her if shes a 4, so inverse law her.
4 / .6 = 6.667
You drink 7 more drinks and magically shes a 4.