If you do get a vibrator stuck in your ass, 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 sphincter and abdominal muscles. Apply as much lube as possible to your rectum without pushing the vibrator further in. Bear down like you're trying to shit the vibrator out. If you can, stretch your asshole 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. If you're lucky, you may be able to get the tail end of the vibrator to clear your sphincter and ease it out of your ass.

If this doesn't work, don't persist for too long, especially if you're in pain. Swallow your pride and get yourself to an emergency room. Yes, it's embarrassing, but it's not the first time it's happened, and it's not the strangest thing anybody's put up their butt by a long stretch. The ER doctors will probably use a speculum to dilate your butt, and then extract the vibrator manually. In extreme cases, abdominal surgery may be required.