b-stub is a noun usually describing Caucasians named Greg who are celebrating either their 19th or 20th birthdays. b-stub is actually an acronym for "be soon tackling un benchmark". This acronym is in broken English with some Spanish elements because it was created on the streets of Mexico. Mexicans used to call 19 or 20 year-old Caucasians in Mexico b-stubs because it was believed that at this age, Caucasians named Greg would face a benchmark in their life and they would have to overcome it(or "tackle" it). It was a rite of passage for Caucasian Gregs in Mexico, and a ceremony would be held, and after the ceremony the Gregs would be garner much more respect from their Mexican brethren.
My friend Greg is gonna be a b-stub tomorrow but I don't know what to get him for a present.