The entire point of this post is in the title. This idea crossed my path yesterday, and I’d like to share it as widely as possible:
Even if we explain that office hours are for students, the students who might benefit the most from having a conversation with us in our offices are the ones who are least likely to show up. It’s a small thing, but calling them “student hours” seems to me like it can help break down the barrier. After all, words matter.
Even if your university only has a small fraction of first-gen students, those are the ones who might be avoiding office hours because they aren’t accustomed to the idea that they’re entitled to your time in that fashion. So changing the name can be just a slight nudge to fix an equity gap.
Small Pond Science 
Terry, I’m now of the gen retiring fast, but I know that while I was at UC Berkeley (research-based, big classes—1000 in my Calculus 1A lecture, etc.), students (maybe even more for women science students from low income circumstances) were often made unwelcome at office hours. I think calling it student hours might have helped redirected the professors’ attitudes from students wasting their time to this time was to help students. Big change at UCB since then, but I don’t think many professors realize how scary
students with certain life experiences can find professors and office hours.
We should also keep in mind that some students may have a negative association with office hours because of grade school experiences. I attended schools where there were few opportunities to interact with teachers outside the classroom and doing so was associated with discipline, like being sent to the principal’s office.