[Niamh.]

I was trying to find out which one is correct and instead got another to add to the list :

a frequent misinterpretation of much older common expression 'fair deuce' meaning fair point, good play (as in tennis), often used informally to recognise good (verbal) comebacks.

Hard to distinguish "do's" from "deuce" particularly given regional and american accents which pronounce "u" as "oo"