The r-scale is much like the f-scale for tornados f1 equals weak tornado f5 equal strong. Except the r-scale is for retards. An R1 is someone with minor down syndrome or some other mild mental retardation. R5 is someone that is a vegetable. R2 to R4 are whatever is in between. then there is pretard for those people that should be deemed retarded but are not.
Example one of word pretard:
Pretard: man that guy has like 20 pounds of kilos of cocaine.
Example two of use of R-scale:
Man 1: hey that girl in the wheelchair over there...
Man 2: yeah what about her?
Man 1: ... shes a stupid R4 waist of skin