"Son ar chistr" (lit. 'Song of cider', also called "Ev chistr ’ta Laou!", lit. 'Drink cider, Laou!') is a traditional song of Brittany, whose words in Breton were written in 1929 by two Morbihan teenagers Jean Bernard and Jean-Marie Prima. The melody was brought to prominence through a 1970 interpretation by famous Breton singer Alan Stivell, and also in 1976 by the Dutch band Bots under the name "Zeven dagen lang".

The song is still used by folk groups around the world and has been translated into many languages. Though many groups keep the popular motif, the lyrics sometimes differ completely from the original. Selected recordings include:

• Elen Guychard - Tudjentil Baod (1940)
• Kevrenn Saint-Malo & Jacques Malard - Ev Chistr Ta Laou! Skaer (1959)
• Alan Stivell — Son Ar Chistr (1970)
• Bots — Zeven dagen lang (1976)
• Frida Boccara — La Mariée (1976)
• Oktoberklub — Was wollen wir trinken (1977)
• Bots — Sieben Tage lang (1980)
• Angelo Branduardi — Gulliver (1980)
• The Chieftains — Ev Chistr 'Ta, Laou! (1987)
• De Höhner — Was wollen wir trinken sieben Tage lang (1995)
• Rapalje — Wat zullen we drinken (1998)
• Scooter — How Much Is the Fish? (1998), (2006)
• Александр Пушной — Почём Камбала? (1999)
• Onkel Tom Angelripper — Medley Aus 6 Liedern (1999)
• Mervent — Ev Sistr (2001)
• Luar Na Lubre — Espiral (2002)
• Blackmore’s Night — All For One (2003)
• Adorned Brood — 7 Tage Lang (2006)
• Ray Fisher, Martin Carthy - Willie's Lady (2006)
• Mickie Krause — Jan Pillemann Otze (2008)
• K.I.Z — Was kostet der Fisch (2009)
• Meldis — Son ar Sistr (2010)
• Tikkey A. Shelyen — Во славу сидра (2011)
• Tom Angelripper (Sodom) — Was wollen wir trinken (2011)
• Tony Junior — Twerk Anthem (2013)
• Anaïs Mitchell, Jefferson Hamer — Willie's Lady (Child 6) (2013)
• Eluveitie — Lvgvs (2017)
• dArtagnan — Was wollen wir trinken (2017)
• Dimitri Vegas, Like Mike — The Chase (2020)

In the Runet, the German version is often believed to be an anthem of the Luftwaffe; this is false as the German lyrics weren't written until the 1970s.^[1]

• (in French) A. Stivell et J-N Verdier, Telenn, la Harpe Bretonne, 2004, p. 123
• (in French) Frédéric Prima, «Son ar chistr. Une chanson qui fait le tour du monde», dans Musique bretonne no 173, juillet 2002, p. 36-37
• (in French) Jean-Marie Prima, «Aux origines d'une chanson... Son ar chistr», dans Musique bretonne no 136, juillet 1995, p. 22-24