The Ground is Lava!
Fun game which begins once someone screams "The ground is lava!!" at the most random time. Everyone else must jump up onto something and avoid the ground or they "die". Best played in classrooms when everyone is quiet, the teacher's face will usually be priceless.
(Class is quiet during test)
Tom: The ground is lava!!!!!!
(Everyone jumps onto of desks)
Tom: The ground is lava!!!!!!
(Everyone jumps onto of desks)