A monster overload is a term given (in Mario games and Super Mario Flash 1 and 2) to a part of which spams of enemies are at a single screen that are commonly used.
Monster overloads are flaws that are commonly used in order make hard levels, most levels can use it for the player to make it almost impossible to pass. It is a rule in the Portal rules.
They can commonly used to lag (or troll) the player's device, and even make it freeze, hang, or even crash. This can be annoying to certain users that are forced to reboot their device's after they hung or crashed.
People frequently removes a lot points if overloads are spotted; the more the user have overloads, the lower the rate will be.