It’s a guy dressed up as the loader from Aliens. And the little Ripley in there is his baby daughter.
Best. Costume. Ever.
I found this on The Mary Sue. And you should check out their update on it because it includes a message from the father who built the costume. He saw their original post on it and wrote in to say how much he loves their site because he wants to raise a proud girl geek.
I’m right there with you, man.