Exhaust Spinners to be exact.
http://www.shoplaser.com/index.html
i thought ive seen everything till now. … .what will they thing of next??? spinned for you anttanna
they already have those you know those little flower things that spin in the wind that you get at k-days 
OMG wat the hell can they do to make a ride more rice next.
Count me in!
that just aint right …reminds me of the boat prop spinner that truck drivers put on the hitches