This occurs when you yank out a tampon that is still relatively un-used. As you take the tampon out, the dry, un-used cotton sticks to the sides of your vaginawall, known as the "wall meat". So you are tugging on your wall meat a little as you take it out.
It's a seriously yuck-o feeling, and all you gentlemen out there are lucky you don't have to feel it.
My tampon didn't go in straight, and now I have to pull it out; let's hope it's not stuck to the meat too badly.