I have seen it a few times, like chewing wintergreen Life Savers, but have found a really bright source - Breathe Right strips. The over packaging is quite large as there are two strips in each, maybe 3" square. I opened a pack when the bathroom light was off and what a light show! A bright blue line of luminescence that starts out the full package width, then splits into two strips, one down each edge, then back to the full width. It’s bright enough to see things, it lights up your hand.
I’ve started using those, because a friend of mine swears his sleep numbers are way up when he uses them. And I think he’s on to something.
But the best part is the triboluminescence. Best to turn out all the lights in the bathroom, wait a bit for your eyes to adjust (you can pee and wash up in the dark, right?), then rip open a pack. And say “Ooooo…”
If you search youtube for triboluminescence you’ll find that the channel Smarter Every Day did an extensive slow-motion video with a very fast camera. There’s tons of good shots of triboluminescence in action in there. Although I’m sure if the packaging on these strips create a stronger effect that he’d be up for doing a re-visit. He was having a lot of fun doing it.