Everyone walks around the room simultaneously. When a walking player says the name of another walking player, the named person must freeze. They can only start walking again when someone else says their name.
Any walking player may say names at any time. Depending on whether the named person is currently walking or standing, the effect reverses — saying a frozen person's name unfreezes them.
This is a great name-learning game that also trains awareness of who is moving and who is standing still.