Source: The Dead Roads, pg(s). 87
Jitterbones resemble halflings with abnormally large heads and loose skeletons whose structure can be controlled by muscle exertion, making them adept contortionists. A typical jitterbone is three feet tall and weighs 35 pounds.
Jitterbones enjoy the taste of marrow, particularly humanoid marrow, and are capable at cracking bones to get to the marrow inside.
Because of their appetite, jitterbones are unwelcome among halflings and often form their own communities in remote fields or forests. Jitterbones determine their hierarchy by the ability to contort one's own body, and often organise macabre 'bone-churning' tournaments to gain or lose privilege.
Some jitterbones live among humans, where they do what normal halflings do: keep a low profile while making themselves useful. However, jitterbones are lazier than halflings and often take jobs that require little effort.