Hide and explode is a Fire Nation game played by schoolchildren. While the rules are not specified, the players do not have to be firebenders, as Aang was able to play the game even though he had not yet begun his firebending training.
When Aang was disguised in Fire Nation school clothes, he was taken to the institute that his outfit indicated he was from. After class, Shoji approached him and invited him to join other students in a game of hide and explode. After the game, a soot-covered Aang returned to the cave where Team Avatar was staying.