Vienna, 21 August 1773: Mozart signs off a letter to his sister Nannerl in his usual jocular manner: ‘oidda – gnagflow Trazom neiw ned 12 tsugua 3771’. This ‘arseways’ spelling of his signature is an early example of Mozart's well-known fondness for jesting and playing with patterns – spatial, arithmetical, linguistic and musical. Mozart appears to have been especially committed to such games in the 1770s. This was a period when he was also involved with the more serious matter of advancing his career, in which the composition of the first six so-called ‘difficult’ yet also ‘popular’ keyboard sonatas, k279–284, played an integral part. This article reads certain inexplicable gestures in the first sonata, k279, as reflecting Mozart's preoccupation with witty expressions at this time, seemingly as part of his attempt to gain the favour of prospective patrons, publishers and employers. The idiosyncrasies of the sonata result from an intersection of the syntax of phrase-level patterning and large-scale form with the semiosis of musical topics, eliciting laughter or simply a smile. Mozart's communicative strategy is situated in a broader context of the compositional play, wit and humour discussed in late eighteenth-century theory and aesthetics. It also allows us to revisit several implications arising from Danuta Mirka and Kofi Agawu's Communication in Eighteenth-Century Music of 2008, including the importance of ‘context’ for successful communication, the susceptibility of eighteenth-century artefacts to present-day misreading and the problem of Kenner, Liebhaber and audiences in general.