LOL Ok, I'd lost the thread.

B/c of how Instead fits inside your body, as well as the Luna (and I'd imagine the Diva and Moon and Keeper) they don't pop out, slide out, push out, or otherwise expel themselves from your body. The Instead sits against your pubic bone, which although your vag muscles *flex* during bowel expulsion, they bone never moves. The Luna (and other cups) work of a gentle suction principle, and I've NEVER had one move. I guess maybe if you're exceptionally full of impacted poop you MIGHT be able to pop it loose.