the act of female masturbation.

can be used as an insult as well as a verb in the same way as wanker is used both as a pejorative and to describe the act of a man masturbating.
"is she mashing it"

or

"that chick is such a masher"

or

if a woman cuts you off in traffic you can yell "you fucking masher"
by Man Lee Man November 1, 2010
When bicyclists, namely fixed-speed riders, dip and weave quickly through cars, skid through them, or a combination of the two.
Mark is one of the best messengers I know. He's so good at Mashing.
by moooosiah March 20, 2009
Mashing is a term commonly used to describe frotteurism. Frotteurism is a type of paraphilia involving sexual urges or sexually arousing fantasies involving bumping or rubbing against a stranger and/or a nonconsenting person for sexual gratifucation.
Frank was arrested for mashing a woman on a crowded subway.
by psychie December 10, 2009
The act of strolling into your local supermarket and heading toward the fruit and veg section. Where you start to masturbate yourself as vigorous as possible, ending with a creamy substance left all over the potatoes, much like Planking became an internet sensation many have taken to Mashing in much the same way.
Andrew: "Look at that girl over there by the tomatoes, she's got her hands right down her knickers."
Richard: "Who? Catherine? Squatting over the Potatoes? She must have her whole fist up there man."
Andrew: "Yeah, she's Mashing hard dude."
by TheDevil'sAdvocate September 15, 2011
Mashing is the act of attacking enemies that are already maimed or significantly impaired as they crawl on the ground. It is highly prominent in video games and commonly accepted among newcomers.
Man one: "Ugh, I've been shoved to the ground and my left arm is gone! Somebody help!"

*noob on the other team comes along*

Man one: " Oh sh..."

*man one is killed*

Man two: "Whoa, man, that noob was Mashing you!"
by Infallible logic March 20, 2009
A derogatory term used in World of Warcraft for classes that take no skill whatsoever to play.
The trend was started on the Firetree US Server by 2 Australian Horde players, It's primarily used to poke fun at and trash talk classes that quite literally "mash" one button and still win in a PvP fight, or top DPS/Heal charts in PvE.

Hunters, Death Knights, Ret Paladins, Disc Priests, Rogues are perfect examples.
Can be written as a single "mash" or many i.e "mash mash" or "mash mash mash" etc.

Can also be coupled with "Nom Nom Nom" to imply "sucking the cock" of their much loved flavor of the month class.

Examples are usually shouted at the computer screen (when losing to one of these no skill classes in PvP/PvE)
or yelled out in Trade Channel to sarcastically impersonate and slander players of the targeted class/es - Can also be considered a form of trolling in WoW.

There are many ways to use "Mash Mash Mash" to trash talk players. Be creative :)
Aubrey: "Hey, you play a lock, you fail at WoW"
Me: "At least i don't play a mash mash Ret Pally"
Aubrey: (to himself) "Shit, i just got owned!"

Some guy sarcastically paying out on Disc Priests in Trade: "Hey, look at me, I'm a Discipline Priest, i run around and mash mash one button (Penance) and no one dies!"

-with the Nom Nom Nom

Paying out on Death Knights and their OPness: "Look at me i Nom Nom Nom my Mash Mash Mash Death Knight, blow Army of the Dead and solo 25 Ulduar!"

Random player slandering Ret Pallies in Trade: "Look at me, i play a Ret Paladin, I Mash Mash Mash one button and everything dies. Nom Nom Nom. Oh look here comes 2 Death Knights, 1 Resto Druid and a Mage, never mind I blow Wings and Mash Mash Mash some more and end up winning, I have skill! Nom Nom Nom!"

Two Warlocks are owning up in world PvP, Drakedog style! Until a Ret Paladin, Death Knight and Disc Priest come in to stop them.

Warlock 1: "WTF! I just got 2 shot by a Relentless geared Mash Mashing Ret Pally!"
Warlock 2: "That's ok, I nearly killed that Nom Nomming Death Knight until that fucking Mash Mash Disc Priest healed him to full with one button, fucking no skill at all!"
Warlock 1: "Yeah, they couldn't handle having their alts rolled by 2 gimp locks they had to bring in their Mash Mash mains in order to win, fucking gay!"
Warlock 2: "At least we don't Nom Nom the Mash Mash classes, we have skill!"
by twowarlockstroyntye January 18, 2010
Being a hot Russian Spy and having a large ghetto booty. Sometimes referred to as mash to the second power.
Wow, did you see that girl? She's got mash.
No dude, she's got mash mash.
by Svetlanna August 11, 2010