So I'm a geologist, but this happened a ways back when I was still in school. One of my classes had recently taken a trip to see an outcrop of igneous intrusions in the local hills. I got invited as a plus one to my fiance's cousin and her now-wife's wedding, and as he and I were driving to the venue, I said "oh hey I know this place, there's dikes everywhere around here!"
He looked at me with this shocked expression, and realizing what I just said sounded like, I hastily explained the geologic definition. He made me promise not to speak a word of it at the wedding.
I've seen the two of them at the occasional Thanksgiving in the years since, and though I find humor in it, I've never felt like I could judge if it would be in poor taste to mention the geology beneath their wedding venue.
(Geology fun fact: if you look at the vertical veins of darker rock, notice the gradient spreading out into the lighter rock. That's where the heat of the intrusion literally baked the older rock, and the pink right at the contact is where the silica actually melted into a glassier form.)
I think that's pretty funny, but as with all terms that could be used derogatively, it's more likely to be considered offensive if you're not a part of the group it describes.
Yeah exactly, which is why I've kept my mouth shut, but I did think Internet strangers might appreciate the humor.
Out of curiosity I googled "lesbian geologists," and while I didn't find an organization or anything, it did lead me to Ammonite, a 2020 film about the first female paleontologist Mary Anning. The film depicts her in a lesbian relationship, and although there's no historical basis, there's also no evidence of her ever being in a heterosexual relationship, leaving it open to question.
I thought it an interesting coincidence that I've just recently finished reading Ammonite, an excellent book by Nicola Griffith about a planet where a virus has wiped out all men, and the exploration of the women-only society that then developed over the centuries.