threesome sex stories

male endowment ?????

on the profile it says average, thick, extra thick / average,
long, extra long, ect..

Question is what is considered average (i have idea that
it is 6" or so, and ...The bigger question?? What is
thickness.? is it circumference, or diameter ( circumference
is diameter x 3.14 (Pi))

I am leaning on the fact it it circumference as some ads say
they are 6" thick. Which is it really?

So what is the measurement that corresponds to the size.

Thanks, Furburgers