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6.
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
 
1.
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 October 31, 2010
 
2.
drving fast
i was mashin down the street.
by mash-in July 14, 2003
 
3.
Combining usually internet or other types of videos whilst some times incorporating music to create a new video that either may be centered around one more themes, or merely to show all of the videos together.
Hes "mashing" together auto-tune remix videos.
by Sir. Kick Ass February 18, 2011
 
4.
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
 
5.
the act of squishing your private parts together.
i walked in on her mashing.it was gross.and stunk.
by bnt07 November 22, 2011
 
7.
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 09, 2009