We ask people who become the photographing subject(s) to smile when taking a picture of a family, team, and group of people by calling “Hai (Say) cheese!” to them.
I think we imported this practice from English speaking countries. I don’t know other variations of “Hai cheese!” than “Waratte – laugh, meaning “Smile!” in Japanese.
Are there any other variations than “Say cheese” being used when taking a photograph in Anglophonic countries?