The sign said "Caution Slow Moving Vehicles Ahead."
I have no idea what this means.
I get that "Caution" is its own thing, but shouldn't it be "slowly moving vehicles"? At the very least, and I think this is still grammatically wonky, it should be "slow-moving vehicles"
Because what the sign means to me is that U-hauls and other moving vehicles are ahead going far more slowly than they ought to be going and I should exercise caution.