1. (MAD) Any situation or course of action which ensures the total erradication of all parties involved.

2. Often used to describe what would have happened in the Cold War Era were one side to have attacked the other using nuclear weapons, causing the other side to retaliate, ensuring the nuclear obliteration of most of Asia and North America.

Of two warring factions, where one group strikes and the other retaliates with the same force, resulting in the obliteration of both.

Happens when one person wittingly shares fluids with another person who is H.I.V. Positive or vice versa.

1. A position whereby the United States and the USSR - Union of Soviet Socialist Republics - would in a nuclear war, be able to destroy each other with their arsenals of nuclear weapons. Each maintaining the possibility to strike the other even if one party fired first. The phrase mutually assured destruction thereby implies that both parties assumed the ability to strike and destroy the other. A catastrophic eventuality if it ever arose. Both parties thus maintained this position, assuring each other than nuclear weapons would not be used, even if a conventional war broke out. The downfall of the Soviet system and emergence of the Russian federation did not make a nuclear war ineffectual, rather it maintains that the two parties still have the capability - and underscores the fact that a nuclear war between these nuclear giants is an inevitability.
2. While this term is specifically used to term the USA and Russia, it may also be applied to China as the latter has built an intercontinental ballistic arsenal that would be deployable if the USA and China ever faced off.

Where two guys face each other, wanking off, and try to have both ejaculates collide in mid-air, thus averting catastrophe.

teachers call it MAD
when two countries come to an understanding that if one country launches an attack the other will retaliate with equal force

Difficult to define exactly, but it's not the actual *name* of a situation or doctrine. Rather, it describes the outcome of a given action in the circumstances:

The outrightly suicidal strategy of nations protecting themselves from nuclear (or, in more recent days, chemical or biological) attack by preparing enough weapons to reduce the attacking country to rubble even as they are themselves wiped out.

Basically, if you're going to be screwed over, make sure the rest of the world is, too.

(MAD) The Cold War strategic doctrine which made all-out nuclear war the only possibility for war between the super-power blocs (US & USSR). Like it or not (and who would?), it worked, at least in preventing the use nuclear weapons in war.