Originally bulls balls, and now also human looking scrotum hanging from underneath the back of a truck. Usually to remind followers that the truck is masculine. Different colors indicate subtle meanings added. Usually considered a redneck acroutrament.
Red truck nuts means the driver is on fire.
Blue truck nuts means he hasn't had any for a while.
Brown and Black truck nuts remind people of the ethnicity of the driver.
Pink truck nuts are for girls that arn't to be messed with, or just like you to know that their car is a boy.
Brass Truck nuts... well you know "he's got brass balls".
A pair of testicles attached to the rear of a car or truck used as an international symbol allowing homosexual men to identify each other.
Red or blue colors are used to indicate if the vehicle owner is a "top" or a "bottom" while other colors indicate "no preference" as well as usual, or unusual preferences.
Size of the nuts have no direct relationship to the actual size of the owner's penis and are usually misleading.
Ricky's heading down to the strip to scope out some truck nuts. He's a red so he wants blue for a night of fun.