A bobble head is a doll found mainly at ballparks, They usually depict some maniaclly grinning, hydrocephalic version of your favorite ballplayers. There are two parts to a bobble head, a body and an oversized head. The two are held together with a spring so that the head can shake and shimmy independent of the body.
The first bobble head was made more than 300 years ago in China -- a grinning Buddha. In Europe, bobble heads were made from fine porcelain. Bobble heads briefly became popular in the US in the 1960's when they were mass produced in Japan from papier mache. Dolls were made for all sorts of public figures from athletes to tv stars to politicians. Many dolls from this time are very collectible.
When I was a wee lad in the 1970's, bobble heads frightened me. I thought they were unnatural. I have a Willie Mays bobble head that I got last year.
Sometimes spelled "bobble-head" or "bobblehead".