Monster - A monster can take many forms, from vampires, werewolves, and zombies, to scientologists and French Canadians. Each different kind of monster requires a different tactic to defeat. In the case of a scientologist, you should just confront them with common sense - they will run away screaming!
Montana - Montana has mountains. Mountains contain threats such as Yetis, Leapords, and Cannibals. Basically everything in the moutains wants to eat you. In conclusion, don't bloody climb mountains.
Mordor - Mordor is a constitional monarchy off the coast of Venuzuela. It is a well-known exporter of jewlery and fanciful rings. Their headquarters is currently based at the top of an active volcano, which seems like a bad idea to me.
Marzipan - "Shudder".
Monkeys - Monkeys carry diseases and like to throw their own feces - both very good reasons to avoid them.
Monk - When fighting evil, monks will always know a ten-thousand year old secret to killing the bad guy. But rather than give this information to you directly, they will instead offer some cryptic advice that will allow you to find the answer on your own (after all of your friends have died). Monk also refers to Tony Shaloub - "shudder".
Madonna - An ancient demon from he dawn of time - she keeps herself alive by consuming the hair of young starlets. Britney Spears was her latest victim.
McDonalds - McDonalds have information concerning an ensuing iceage that could end humanity. To combat this, they wish to overfeed the nation to the point that we can all hibernate through the approaching winter by sustaining ourself with the high-levels of stored body fat - much like a North American bear.
Monty O'Bama - The president's "special" cousin that lives in the attic of The Whitehouse. He likes to eat salmon on Tuesdays, but prefers to eat crayons on all other days.
Mission - Any mission in a horror film will begin with a team of cocksure marines that are going into a 'hotzone' to control a relatively mundane threat. Due to some unfortunate set of circustances, the situation will escalate to involve sand demons and devil worshippers, or some sort of ancient creatures released from that cave made out of skulls that they probably should have left alone.
Missile Launcher - If you find yourself in a fight with a Tyrant - a biological weaponised mutant-thingy - then you will at some point need to find a missile launcher to defeat it. You will not find one at first, but rest assured that one will cnveniently present itself to you towards the end of the film.