I want to begin by saying that the "cool girl" does not exist. She is a fantasy that both men and women buy into. She is a collection of attributes; a figment of the straight male imagination. She's a perfect role to inhabit in your 20's when you're unsure of yourself.
While I had inner turmoil about being an easy going and complicit woman to appease men in my undergrad, I didn't have the vocabulary to express how I felt about it. We all know the "cool girl", the one who goes out of her way to say that she gets along with men better than women because they're "less drama". She doesn't really ask anything of her man, and she certainly doesn't complain about casual misogyny or sexist jokes.
Canadian women’s rights advocate Julie Lalonde stated, “There’s this idea that if you distance yourself from other women and align yourself with men, not only will they ‘choose you’ over other women, but they will treat you with the same respect they show their friends. It’s a phenomenon known as ‘proximity to power’: the idea that aligning yourself with the person/group in power will give you access to said power.” However, being the "cool girl" doesn't grant you access to the "boys club" and it never will. Men won't take you any more seriously than any other woman. In the end, it gets you nowhere.
I quickly came to realize that I would not and could not be the "cool girl". It ultimately wouldn't make me happy. In reality, the "cool girl" is powerless and silent. Her perspective becomes his perspective. She is basically a glorified doormat. So, be brave. Choose to be the "other girls" instead of the "cool girl". I promise that you'll like yourself a lot more in the end, and that's what matters, right?