‘Mondegreen’ was a collaboration between Millar and the Canadian artist Geoffrey Farmer, which took place at Project Arts Centre, Dublin, 7 July–20 August 2011. It took the form of a 'sculpture-play', which ran for approximately nine-and-a-half hours every day, over the entire exhibition run of seven weeks: an attempt to create a new form of performance and exhibition-making.

The title ‘Mondegreen’ refers to a mishearing, usually in song lyrics, and the exhibition explored both artists’ fascination with the slippages that occur in the retelling of a story. The story was simple – the replaying of a day the artists spent together supposedly to discuss what they would exhibit – yet drawn into the narrative were a diverse range of characters and cultural acts, from the pedagogical methods of Pythagoras to the chance operations of John Cage; Joyce’s recreation, in Ulysses, of a single day was another obvious influence. Millar gathered research material from diverse sources and selected on the basis of affinities found between them.
The gallery’s opening hours were altered to replicate the day the artists spent together. The score’s recital occurred daily, performed by a designated individual who activated the changing scenography and sound components. The ways in which these actions were choreographed was deliberate, established to work between the predefined and the interpretative; a frame creating distance between authorship, control and happenstance.

As Isobel Harbison wrote in Frieze (2011), ‘Despite the potential pitfalls of an arranged artist pairing and an exhibition that struck so ambitiously across disciplines, “Mondegreen” succeeded in a variety of ways…Avoiding a wearying exercise in reading on our feet, or another fatiguing object–association sculpture whose common elements remain innocuous and undisclosed, this work was as lucid and generous in fragments as it was in its entirety.’