Hard to distinguish "do's" from "deuce" particularly given regional and american accents which pronounce "u" as "oo"
"fair deuce" (fair do's)
If something good happens to you it's fair do's, if something bad happens to you it's fair do's
or if you havent listened to the question you were just asked, or the answer you just recieved, fair do's will make everything ok, enjoy XD
2nd person: Wow how did you do that?
1st person: I revised, bla bla bla yadda yadda yadda blaaa
2nd person: ohhhhhh fair do's