Do one legged ducks swim in circles? Its a way of saying "of course" and being a little bit of an asshole at the same time, and is probably only spoken by poor white people in the southern parts of The United States. An example: "Are you getting drunk tonight?" "Do one legged ducks swim in circles?"

dumb as a box of rocks - not very intelligent

the fly in the ointment : something oor someone that is ​spoiling a ​situation that could have been very ​positive or ​enjoyable: ps:i learned that idiom when i was reading a marvel comic named "x-factor" :)