MST

Short for "Mary Sue Torture" Usually used in fanfiction. A form of mockery in which an author takes another author's piece, and breaks it up. They generally mock each and every line, pointing out any and all typos and/or grammatical errors along the way.

Work being MST'd: And he carryed her back to merkenwood,
Author MST-ing: O.O I don't even know where to start on that one...

MST

Stands for MBI Standard Time, a time system used by the MIS Bureau of Investigation. The system sets 13:00 as 0, and adds or removes the appropriate amount of hours for whatever time is being converted to and from MST to other time formats.

Ellie: Hey Big Man! You wanna study tomorrow?
Big Man: Yes!
Ellie: What time?
Big Man: 0 MST.

MSTS

Known among railroad nerds, this computer game was released in 2001 and officially called Microsoft Train Simulator. Now it is overused and still very slow on many computers.

Railroad nerd: Hey man, did you get the new update for MSTS?

Friend: No, I can't get it to run on my computer.

MST

Acronym for "Metric Shit Tonne"

John: "I've been away for a week, and had an MST of work to catch up on today!"

MST

duPont Manual High School's Math Science Technology program. Pure evil. With Mr. and Mrs. Z and Sha-- Ms. Johnson.

DUDE did you have all of your MST classes today?

MST

Short for "Money Saving Tip". Coined by actor/comedian Dewayne Perkins.

MST: When staying at a hotel, immediately put all cosmetic products into a bag, then call housekeeping claiming to not have been issued the products in the first place, then repeat twice a day, until you have as many as possible.

MST

A tattoo on a female's lower back - an acronym representing "mid section tattoo" or alternatively "money shot target".

"Dude, check out the MST on that chick! I'd hit that all night!"