I took on an internship at a software company several months ago. When I interviewed and visited the office, everybody was very nice and I felt I would fit in.

As time has passed, I think people have gotten very "comfortable" and "casual" and I am no longer comfortable with the culture in the office. There are a lot of mean jokes and it feels very awkward to be a female developer here (there have been two instances when nudie calendars have showed up in the office, much to the amusement of everybody else - there is much more but I want to keep this short). I feel like an outcast and wish I could have predicted this shift in culture.

What are some indicators I could look for next time?

edit: not totally cool with the duplicate mark, I should have been more clear in that I was looking for indicators of underlying bro culture/general weirdness about stuff relating to women, especially in software.