People from Dublin 4. Posh area, people that wear dubarrys or abercrombie are usually called D4's. An insult to people from other places or "posh" people.
D4 Girl: Oh my gawdd, roysh daddy bough me this amaaaaazing abercrombie tee today and it sooo goes with my uggs roysh!
2nd D4 Girl: Oh my gawdd that sounds like brill! Lets go drive around in the lexus and laugh at skobies.
D4 Girl: Oh. My. Gawddd. One called us D4s i was like yeah, roysh! *laughs*