I’m not sure where the humor comes in here.
In case you can’t read the text below it says:
Girls are great. So why are girl superheros always so crappy? Because of boobs? Probably because of boobs.
Vote on the worst one now.
You can see it here

Here’s the website of the editor of this site, you know in case this bothers you.
http://www.streeterseidell.com/
and he’s on Twitter too.