Prosthetic testicles used to adorn the oversized vehicles of those who think very highly of themselves.

They aren't entertaining and they don't make you look cool.
They are contrived and make you look uneducated.
Jeff hung a pair of bumper nuts on his Tacoma.
Jeff's truck only shuttles him to and from work and the grocery store.
He did take it off-road once, and ironically his ground clearance was insufficient to prevent a rock from removing a portion of his oil pan and wrenching the faux balls of his otherwise unused trailer hitch.
by Fieldgrunt March 22, 2007
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Imitation bull's ball made of chromed steel or colored plastic, that are hung from the rear bumper of pick up trucks and sport utility vehicles. See see bumper balls
Ihung some chrome bumper nuts on my f-350 dually.
by bumperman March 22, 2005
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" billy you are not a grown man yet, you first have to grow some hair on that lil nut bumper of yours you got there"
by THE 69 OMEN July 22, 2008
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