Diluting wine with water, also known as baptising wine, was a common medieval practice. Taverners (innkeepers) and vintners (wine merchants) were especially associated with this custom. Literary accounts sometimes depicted them as nefarious figures who mixed wine with water in order to maximize their profit. Ironically, at the same period drinking diluted wine was associated with the virtue of temperance; in contrast, the excessive drinking of wine was associated with the deadly sin of gluttony (gula).
The Joyful Ballad is essentially a catalogue of curses that the poet wished upon taverners who diluted their wine. Although its author is unknown, it has long been associated with François Villon (c. 1431–after 1463), one of the most renowned French poets of the late Middle Ages, but also a murderer, thief and vagabond. blogs.bl.uk