It's like a frat, but with all girls.
Ya know, at the lady frat, it's literally a sorority.
A girl who has a hyper fixation on frat boys, hence the ‘crazy’.
it is also a play on words from the term ‘crazy cat lady’
guy 1: yooo guess who got a date with jessica
guy 2: don’t feel special, that girl is a crazy frat lady.