It is said that Lundy Foot, a Dublin tobacconist, set up his carriage, and asked Emmett to furnish him with a motto. The words of the motto chosen were Quid rides. The witticism is, however, attributed to H. Callender also, who, we are assured, supplied it to one Brandon, a London tobacconist.
“Rides,” in English, one syllable. In Latin (why do you laugh?) it is a word of two syllables.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894