I recently thought about this and wanted to share mine.
Feel free to share something that happened to you/someone you're close to below.
I was on a school trip and decided to visit some friends while I was there (this is not uncommon where I'm from).
I had to travel a little to see my friends, and on the way there, I realised that I may have started my period. It came a week early and I had a menstrual cup on me, but I realised I'd have to open my luggage and go to the restroom at my friend's absolutely TINY place, which made me feel really uncomfortable.
I looked for a tampon desperately while on the train and luckily found one. I put it into my pocket and after I got off the train I greeted my friends, talked to them for about an hour and had dinner with them before finally being able to excuse myself to the restroom.
I inserted my tampon, watched a movie with my friends, got rid of the tampon and inserted my menstrual cup, greeted their spouses, talked to them for a while and then went to bed.
Officially, at least. In reality, I was wide awake until 2am, which is when I got up to empty my menstrual cup in the most quiet way possible. I was so embarassed to be on my period at their place that I didn't want to tell anyone.
I then went to sleep in beautiful, crispy, fresh white linen.
I woke up with a racing heart at 4:30am and couldn't tell why. I wanted to get up to pee, but I quickly realised that if I did, I'd cover everything in blood.
I had woken up because I had felt blood coming down my leg. I always sleep in a very sheet-protective way when I'm on my period and throughout the years, I've found the best ways to avoid bleeding on sheets.
However, I knew that I'd have to remain in the same position until at least 7:30am, which is when everyone would be off to work and I would finally be able to get up without anyone seeing me.
I had to be completely quiet for 3h, I couldn't even grab my phone or go back to sleep. Instead, I waited until I was sure everyone had left, rolled out of bed to not stain anything with my blood, quickly got up and ran to the bathroom.
It was a lot worse than I had expected - I left an actual trail of blood behind and by the time I got into the shower to rinse myself off, everything was full with blood, including my clothes. I made sure to clean everything up (I'm a very tidy person and hate making a bad impression, so you really couldn't tell my blood had been on the floor), packed my things and headed for the airport because it was my last day of that trip.
I planned my journey home in a way that allowed for restroom breaks every 45 minutes.
I had to use the restroom inside the train, at the airport, in the plane (multiple times), at the other airport and at a train station until I was finally home.
Be kind to others - you don't know what they're going through
Nobody knew, I never told anyone this happened and to this day, this is a memory that haunts me because I was in so much pain, I had to find restrooms on the go while sticking to my tight travel schedule all the while travelling on my own.