For ages going back to the Greek gods and the Egyptian queens the J-factor has always been attributed or linked to women. Most people would agree and lean towards the idea that women are the jealous type.  That may be true, However, men also have the ability to fall under the trap of jealousy.  It is not something men will admit, lets look at a few things that guys might get a bit jealous about.
The born wealthy.. Yeah! there are people in this world who are blessed enough to be born into wealth.  We hate these people.  These people have no idea what the real world is like.  something similar to Buddha before he left his kingdom.  Most of these people end up getting whatever they want, and don't have to work for it.  This is something most of us would love, but don't have and as a result we do feel the rage of jealousy. 
Most guys understand that people like Brad Pitt and Tom Cruise are blessed enough to be good-lookin dudes, and can actually act.  As a result, they are rewarded handsomely with Angelina Jolie, a ton of money :).  That is something most guys can digest a bit.  The fact that some guys just seem to be born with it.  What we cannot stand are the jokers like Shilpa and Rakhee Sawant who make loads of money for talking rubbish in a useless TV show and buying and running cricket clubs.  This is something most guys are jealous of, however we'd be willing to switch spots with them in a heart beat! :)
Oh how can I forget to mention the kind of guys whom i am most jealous of.. "The slim gluttons". I'm NOT jealous of a guy that eats healthy, works out six hours a day and is in the best shape of his life.  I AM jealous of the jerk that brushes his teeth with french fries, and eats 15 zinger burgers a day and washes all that down with a gallon of choco milkshake, and still is in the best shape of his life.  This jerk, I just cannot stand :( .  We hate this jerk so much. While we suffer from heart attacks, he picks up another newly single women, and he's always full and burps heartily.  What a jerk!.
Hmm, I hate to say this but Guys at times, can be jealous of women. Every time a woman bats her eyes and gets out of a traffic police man, or the when she gets a separate counter to book tickets whereas it's already waiting list -2 when my turn arrives, or has someone at a retail store show her "extra" customer service....grrr it freakin drives me nuts.  The reason it drives me nuts, is because no matter how politely I talk and how much ever I be nice to them, I know I will never get the same type of treatment.  Its a shame, and it doesn't have to be that way.  Unfortunately, I just have to know that if I'm lost in a park and need to find a way out, I'm gonna have to do it my damn self.
u see.. guys can be jealous too !!! But, the difference lies in how guys deal with these things differently from the way women do.