Men's Rights Activist. Someone who thinks that just because there are places where men may receive special treatment doesn't mean it's ok for them to be discriminated against in other places, such as custody in divorces.
A common misconception is that a MRA can't also be an ERA (equal rights activist), wanting equality for both sexes. This is because many people are stupid fucking morons who think straw man arguments are logical and everything must be an extreme
If thinking I shouldn't get primary custody unless my wife is a crackhead makes me a "men's rights activist" then call me an MRA. But I still think women should receive equal pay for equal work.