It was a classroom game called "7-Up". Seven kid went to the front of the room, everyone else put their heads down and thumbs up. Those who were 'it" tiptoed around and gently put someone's thumb down. Once they were all back up front, everyone would put their heads back up and those who had been tapped would stand up and take turns trying to guess who had tapped them. If you guessed correctly, you took their place up front.
It was just one of those games we'd play with the kids when we were ready a little too early for lunch/music/gym/whatever - when there was not enough time to start the next subject, but it was too early to leave and have them waiting noisily in the hall.