A person who consistantly tells white lies and/or often exaggerates situations (most often a child)
My daughter tends to be a fibulator when she is put on the spot.
All politicians nowadays are fibulators, like in Jane Nazrat's poem "The Tribulation of Fibulation", you can check it out on Think.mtv.com.
A chronic liar who works in the hospital, where lots of defibrillators are found. Often a member of management or administration.
"Hey, I heard our on-call pay was no longer going to be taxed as a bonus!"
"That's crap, honey. It came out of the mouth of a fibulator in cardiology."