The opposite of a femboy, a masgirl is a masculine female and usually participates in crossdressing, and various other activities usually associated with men.
Any female who is more masculine than her boyfriend. Her physique is typically bulkier than that of her significant other. She also has a deeper voice and weighs more. It's speculated that mangirlfriends even have more facial hair than their boyfriends.
On top of all of this, a mangirlfriend is usually ugly as shit. If one didn't know she was a girl, one would swear she was a bear. Once one discovers she's a girl, one immediately assumes she's a lesbian.
But no, she is in fact straight, and usually extra slutty in hopes of proving this. A mangirlfriend's boyfriend is typically either desperate for companionship or is basically on the verge of being a twink. If the latter is the case, the difference in masculinity is extra humorous.
Mortimer: "What the hell? Why is Jacob sitting in his girlfriend's lap? Shouldn't it be the other way around?"
Jimi: "MANGIRLFRIEND!"
Kaylee: "Fuck Austin and his fucking mangirlfriend!"
Ajay: "Hey watch out, he might have her beat you up."
A well-known Troll in the IMDB community. On July 22nd, MJsGirl launched a campaign against Clerks II on the IMDB message boards, claiming that Kevin Smith belonged in jail and that Blacks didn't know what was offensive because they're less educated. Despite saying all of this, she constantly reiterated that she is a "liberal progressive" and that everything she says is right. She soon broadened her campaign to include Jim Norton, "Lucky Louie", Opie & Anthony, Trey Parker, and Matt Stone. Shortly after, she began to resort to tactics such as threatening lawsuits and claiming that she had been so troubled by peoples responses to her that she was being forced to see a psychiatrist. This failed to win her support, however, and she remains IMDB's most hated user.