A fork of Rural Dictionary
When you are so tired your head falls violently rearward, as if you were just shot in the head.
"Damn Jeff, are you allright?"
"Yeah man, I'm so tired, just keep JFK'ing"
When you duct tape a 12X scope onto your member, then proceed to ejaculate onto a cardboard cutout of JFK and his wife across the room.
JFK'ing it; Example- me and my friend were messing around and I accidentally JFK'd it on John face.