Les Calmars is a restaurant in Sing. The restaurant is most notable for its large presence of luminescent squids that are used for lighting purposes.
A few minutes into Sing, Buster Moon discusses plans to revitalize the Moon Theater by having a singing competition, to his friend Eddie's doubt. The two are kicked out of the building (with Buster being literally thrown out) after they bring in outside food.
Buster is later seen placing posters against the glass encasement for the squids to light up the Moon Theater's stage.