Like at the plow day in PA.
After I had been plowing, I went over to enter the pull they had. Well, now, about 1/2 way around one of the "tech inspectors", pointed and asked, "Hey, what's that green stuff in your tire treads there?"
"Oh that?" I replied, "Slow Deere." and he waved me through.
And I own green myself, but that there is funny!