Soldato
JDM scene kid thing. Let's everyone know I'm a ****.
It's a hang ring or 'Tsurikawa' as found on Japanese public transport.
Years ago, people in the japanese modified car scene would steal them and hang them from the back of their cars as a sign of defiance, and then it sort of evolved into a commercially available drift charm. Some say when it drags along the floor you know your car is lowered enough...
I guess you could remove it, if it's been stuck on by previous owner. Same with the nite nite kids thing.