an S.I. scale of measurement for the tip of a girls boobs to the back of her ass. No individual over 280 pounds can be used for such scale, and "zero" assumes that the individual has no ass and no boobs, while a "ten" means the individual has pamela andersonesque breasts and a jlo-like ass.
John: dude my gf has a huge ass but is lacking in the titty department
Dan: yeah man, shes about a 4 on the cheech scale. My girl has huge boobs and a mediocre ass. shes like a 6 or 7
John: what about zacks mom!?
Dan: yeah, shes like 300 pounds bro. she doesnt apply