I can only second what Gummy has said about tampons getting stuck in the vagina (there was a sort of epedemic of stuck tampons back in the late seventies and early 80's with the rise and fall of the ultra-absorbent tampon) and about dildos and vibrators getting lost in the rectum.
However, I don't think that a penis sized vibrator or dildo could "get stuck" in a vagina, unless the woman maybe suffered from a rather extreme bout of severe involuntary cramping.
The problem with tampons getting stuck is caused either by the tearing of the little string, or because it hasn't soaked itself completely, and well, I can't see how you could suddenly loose grip of a normal sized vibrator/dildo. The problem with inserting ordinary toys (without a base) into the rectum comes from the strentgh of the sphincter muscle that closes your anus. It *wants* to be closed, unless you release it, and once you've shoved something past there and loose grip (and it doesn't have a base), it's almost impossible to get it out without the help of a doc.
The vagina isn't a "bottomless pit" (quite in contrast to the anus), and while it too is made up of strong muscles and can accomodate almost any size penis, several fingers or a hand, and -after the hefty stretching happening at birth- even a baby's head, I first of all don't see how one could fit the entire length of a normal sized vibrator/dildo in there and I don't see what would have to happen muscle wise so that you can't manage to get it out again.
"Through repetition the magic will be forced to rise."