Twinkle Toes

When two people independently say or do something at the same time, it is customary for one to shout: "Twinkle toes!" and begin counting. Not sure why on the counting, but that's all I got.

Mary and John both said, "I wish you were here" at the same moment while talking on their phones. Mary exclaimed, "Twinkle toes!" and John just laughed.