If you get a vibrator stuck in your vagina, turn it off (if you can
reach the controls). If the vibrator has an external battery pack,
remove the batteries. Take deep breaths and try to relax your vagina
and abdominal muscles. Apply as much lube as possible to your vagina
without pushing the vibrator further in. Bear down like you're trying
to give birth to the vibrator. If you can, stretch your vagina by
inserting two or three fingers and spreading them. If the vibrator has
wires attached from a battery or control pack, be careful when pulling
on them, as them may detach.
Because the vagina is relatively short, you should be able to get the
vibrator out. If you can't, and if you are experiencing pain, your
pelvic and vaginal muscles are probably spasming and you need medical
attention. Go to the emergency room. Yes, it's embarrassing, but
they've seen everything. They'll give you something to relax the
muscles and will extract the device manually.