A sarcastic rejoinder feigning gentle surprise at another person's naive, glib, obvious, half-
baked or banal observation. (abbrev. of "Do you really think so?")
cf.
DUH
Person #1: "Gee... outfitting all my bridesmaids in Vera
Wang and
Manolo Blahniks might eat into my bridal
budget..." Person #2: "Ya thank??"