When you call out “sick” from menstrual cramps, how do you explain to your boss? (Please read)

(DISCLAIMER: If you’ve never had cramps bad enough to warrant calling out of work, PLEASE DO NOT COMMENT on how I should just “suck it up.” 95% of the time I go to work when I’m on my period but every once in a while I just can’t take it and it’s not productive for me to go into work and not be able to focus because I’m in pain.

It wouldn’t even be calling out of work, it would just be working from home. And my boss honestly doesn’t care if I work from home once in a while anyway, so it’s not like it’s a big deal at all to stay home once in a while, regardless of the reason. )

So even though I know she won’t care if I ask to work from home, she will ask why (though im 100% sure she’ll say it’s fine regardless of my answer). I’m just wondering if for something like this, you’d actually say it’s because of cramps or would white lie to avoid talking about your period to your boss, and say something vague about “not feeling well” (but then I don’t want her to worry that I’m sick...) or just make up an entirely new reason (something like... Im waiting for a repairman or I have dinner plans with out of town relatives and it’d be more efficient for me to be home.)

Again, a reason of something dumb that would be fine with her lol, that’s how little she’d care about me staying home, but just wondering if it’s better to white lie and make up a reason to avoid talking about my vaginal bleeding at work...