It was described in a novel L’ecume des Jours by Boris Vian:
For each note there’s a corresponding drink – either a wine, spirit, liqueur or fruit juice. The loud pedal puts in egg flip and the soft pedal adds ice. For soda you play a cadenza in F sharp. The quantities depend on how long a note is held – you get the sixteenth of a measure for a hemidemisemiquaver; a whole measure for a black note; and four measures for a semibreve. When you play a slow tune, then tone comes into control to prevent the amounts growing too large and the drink getting too big for a cocktail – but the alcoholic content remains unchanged. And, depending on the length of the tune, you can, if you like, vary the measures used, reducing them, say, to a hundredth in order to get a drink taking advantage of all the harmonics, by means of an adjustment on the side.
And here it is, realized:
(Porkpie pirouet: Adriana Lleras-Muney)