Fernacular grew "tired of guys having no idea why girls find female superheroes' costumes kinda sexist", so she made the series of drawings below to achieve three main goals:
1) Make it so the first thing you think of when you look at them is sex, whether you want to or not. 2) make it so that any male human who looks at this feels really uncomfortable. 3) make it funny, because, well, it's kinda hilarious really. [Fernacular]
While pointing out that female superheroes often wear impractical, stripper-ish costumes is nothing new -- see the banner picture, Kate Beaton's Strong Female Characters, and the alternate Avengers poster for more examples -- I like her execution.