I know that when you are taking a photo you ask the subjects to say cheese as saying the word 'cheese' make you mouth form a smile shape. What do they say in other European countries? The French don't say 'fromage', that just a bad english joke.
In Denmark we say "appelsin", it means orange (the fruit, not the colour) :-), sometimes we say, "say cheese" but i guess that comes from watching too many movies :-)
In the eighteenth century they used to say, Prunes and prisms, because that made the lips take up a heart shape - a bit like marilyn's boop boop ie doo - and drive those Regency beaux quite insensible.