Mozart - Difficile lectu

K. 559 was evidently meant entirely for fun. The work features two bilingual puns and some scatological humor. The lyrics are-ostensibly-in Latin, though as they are given in sequence they do not make sense in this language:
Difficile lectu mihi mars et jonicu difficile.
The humor of the work consists of hearing these words instead as vulgar phrases of German and Italian.
The German pun is based on the strong Bavarian accent of the tenor-baritone Johann Nepomuk Peyerl who can be presumed to have been the lead singer in the first performance As Jean-Victor Hocquard points out, the pseudo-Latin lyrics lectu mihi mars, as Peyerl would have sung them, resemble Bavarian German leck du mi im Arsch,which in a literal English rendering is "lick thou me in-the arse". More idiomatically, the phrase could be translated, "kiss my arse"
The second pun in the canon is based on the single Latin word jonicu. Winternitz (1958) explains that when this word is sung repeatedly and rapidly, as in the canon, its syllables are liable to be heard rearranged as a taboo word of Italian, cujoni, which means "balls, testicles"; see also Cojones.