just a few ideas

or they find ways to get over on the system (stay ahead of "the man") skate by

another suggestion

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http://www.proz.com/kudoz/english_to_spanish/idioms_maxims_s...

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Note added at 9 mins (2011-05-25 22:16:29 GMT)
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http://www.wordreference.com/es/translation.asp?tranword=sys...

Concise Oxford Spanish Dictionary © 2009 Oxford University Press:

he tried to beat the system ~ intentó burlar el sistema

buck the system
to fight against the usual way of doing something Tom spent much of his working life bucking the system, which explains why he didn't get many promotions.
http://idioms.thefreedictionary.com/buck the system

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I think I should **buck the system** more at work. instead of bein' so ...
13 Jun 2008 ... Read I think I should buck the system more at work. instead of bein' so good natured by Brian on Myspace. Social entertainment powered by ...
www.myspace.com/brian_w_dubyah/blog/405298839 - Cached

#
Peter the Great - Government Reforms
He stifled initiative and such was his reputation, everybody worked in the way Peter wanted them to work. Few had the courage to **buck the system** in case ...
www.historylearningsite.co.uk › Peter the Great - Cached - Similar
#
Review of Brazil
31 Oct 1997... to the studio work of various pop musicians and groups like Eric ... the movie who is a renegade plumber and loves to **buck the system**. ...
www.challengingdestiny.com/reviews/brazil_sound.htm - Cached

Consider:

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t's not nice to fool the IRS F*cked News. ... Go Back ?? fuckedgaijin > General > F*cked News · Reload this Page It's not nice to fool the IRS ...
www.fuckedgaijin.com › fuckedgaijin › General › F*cked News - Cached

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23 Feb 2008 ... Protected: You Can't Fool The IRS – Palm Spring Man Convicted in Scheme to Defraud IRS! Choices and Consequences says Ethics Speaker Chuck ...
chuckgallagher.wordpress.com/.../you-cant-fool-the-irs-palm-spring-man-convicted-in-scheme-to-defraud-irs-choices-and-consequenc... - Cached - Similar

Saludos!
eski :))

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Dec 2007 ... This instruction will show you how to Fool a fingerprint security system as easy as ABC. IBM never want you to know about,. it works for ...
www.instructables.com/.../How-To-Fool-a-Fingerprint-Securit... - Cached -

or 'ridiculed' as the case my be.

Suggestion

Since you said "in a job, they pretend to work but they don't do it" I think this will work. This is "milking the clock" but only if they are paid hourly.

This is one of the common meanings, but it all depends on the context. See:

Wikipedia:Gaming the system - Wikipedia, the free encyclopediaEditors typically game the system to make a point, to further an edit war ...

The meaning of 'gaming the system' - Examples - Spurious legalisms
en.wikipedia.org/wiki/Wikipedia:Gaming_the_system

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Note added at 6 hrs (2011-05-26 04:17:51 GMT)
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Without context, it's' hard to tell exactly what is meant. My suggestion implies that the person uses the system to achieve outcomes it was not intended to produce. It is enlisted to produce unintended results. That's quite different from getting around the system.

Examples:

Verb
game the system (third-person singular simple present games the system, present participle gaming the system, simple past and past participle gamed the system)
1. To use the rules and procedures meant to protect a system in order to instead manipulate the system for a desired outcome.
http://en.wiktionary.org/wiki/game_the_system

game the system: to manipulate and take unfair advantage of loopholes in rules and regulations in order to make that system of rules and regulations work to your own advantage in risky, typically illegal, schemes
http://encarta.msn.com/dictionary_1861614274/game.html

Jun 30, 2009 ... Once they've established their mastery, the next step is to figure out how to “game” the system, meaning that they will discover and define ...
opusresearch.net/.../nytimes-column-highlights-google-voices-transcription-shortcomings/

I'm accustomed to seeing "burlar al sistema" used in the context of rejecting the rules, circumventing, or maybe even subverting rules and norms. A specific context would help in deciding what exactly the person would be thumbing his or her nose at. Examples:He was given multiple warnings and metaphorically thumbed his nose at his boss. Now he's a folk hero? What's the over/under on number of ...
blogs.chicagotribune.com/.../the-car-salesman-who-wouldnt-take-off-his-packer-tie-deserved-to-get-the-sack.html?... - En caché;Why would a man in Detroit "thumb his nose" at his boss? ...
www.funtrivia.com/en/subtopics/All-Thumbs-306871.html; If someone disrespects you, you can say that person is thumbing their nose at you.
If you tell someone you are sad and they laugh at you, you can say they are thumbing their nose at you.
If you tell your boss you are ill and she says you have to work anyway, your boss is thumbing her nose at you.
If you ask your neighbors to turn the music down, and they turn it up, they are thumbing their noses at you.http://www.englishbaby.com/lessons/1672/slang/thumb_their_no...

I think it would also be a suitable translation, but without more context it is kinda hard to be sure.