neck snap
When you fling your body forwards but your head doesn't cooperate. In order for something to be a true neck snap, the actual snap must be accompanied by an audible popping sound.
Dude!, that car accident gave me a total neck snap!

That bitch tossed me around the bed and gave me a really bad neck snap.

That wooden roller coaster ride gave me the neck snap! My neck has been sore for weeks.

That old guy tripped on the sidewalk and popped a disk. What a neck snap!