So this is more of an amusing anecdote than anything, but I though y'all might get a kick out of it.
I'm about mid-bleed, which lately has been fairly heavy. I use an Instead cup most of the time. With the more...horizontal? insertion of the Instead (as opposed the the vertical style of reusable cups), you can pretty easily get a little air bubble trapped in the bag portion of the cup. Generally, I do a little kiegel-squeeze right after I put a new one in, to avoid annoying blood-queefs later on.
I'd put a new one in this morning, and noticed my flow was pretty heavy, fresh blood. Ran around, had some breakfast, took a walk, came home at sat at the computer. Sort of ignored the "full now!" sensation from the cup (I don't know about everyone else, but when my cup is full, it registers as a weird sort of pressure for me).
I think I shifted positions in my chair or something, and all of a sudden, the most bizarre, disturbingly loud keening squealy burbling noise escaped from the region of my nethers. You ever have a not-so-bright dog that farts and then questioningly looks at its own butt, like "what just happened"? I think I made that face. The sound was not unlike stretching the open neck of a full balloon and letting the air out slowly. Only...wetter. Like maybe you'd been amusing yourself for a while with the same balloon and it was all spitty inside.
Did a quick hand-down-the-pants check and realized I'd completely lost cup integrity. Woosh! Like it had an emergency over-ride dumping system in place, it had given up its entire capacity.
Mental note: If your vagina is singing, it's time to change the dang cup.