Barstool is a humorous site poking fun at all things sports. Nothing on it is meant to be or should be taken seriously. Sure joking about rape probably isn't the best thing to do, but it is clearly a joke and not meant to encourage the conduct.
Tongue in cheek is one thing, but writing that "if you're a size 6 and you're wearing skinny jeans you kind of deserve to be raped" is offensive and completely unacceptable in any context.
Even if you can claim that these things are "fratire," condoning that sort of humor and supporting the people / entities that use it normalizes rape, sexual assault, and degradation of women. In other words, if you don't speak out when people make those kinds of jokes, writing them off as mere "shock humor," you deny the severity of the subject matter. It minimizes the reality that rape and sexual assault actual do happen to normal people -- all of the time -- and it is not a laughing matter to them or to the people who love them.
Some things are just not okay to joke about. We should have the same attitude in our culture about rape humor that we have about people who use racial slurs to get a laugh.