Céilidh callers? Is that a thing? I thought it was only in square dances that instructions were shouted out, on the basis that square dances involved people from Scandinavia, Germany, Ireland, France, England, etc, whose dances are similar but not the same and so people might like to know if they were to pass back-to-back - Dos a dos - or whatever. But I've never heard anyone giving instructions at a céilí, not even when I managed to set a whole dance hall at odds by giving the odds in the Ladies' Chain in a sixteen-hand reel.