What to wear as Sarah Carter: A black tank top and pants, absolutely drenched in blood. Like, dump a bucket of red paint on yourself, then jump into an Olympic-size pool full of pizza sauce, and then have someone throw tomatoes at you. You might want to bring along a spelunker's helmet so people know for sure who you are.
How to act as Sarah Carter: Well, you just watched a bunch of your friends be viciously murdered by cannibalistic monsters, so behave accordingly.