Regardez plutôt dans le Urban Dictionary, une mine de définitions en anglais slang (argot) alimentées par les internautes eux-mêmes. Voici ce que j'ai trouvé pour YUP:
Young Urban Person
People in their early till late twenties, who have made bucks
in business with sheer luck (mostly during the internet
hype in the late 90ties).
Can be recognized standing in bars boring the shit out
of most good looking woman and/or bragging about
there just bought second hand porsche or leased Audi A4.
They are mostly neatly dressed in suits with their hair
glued into shape with too much wax/hairgel and some
dandruff residing on their shoulders. Always very
neatly shaven and their skin as clean and smooth
as their pimples allow it to be.