States love jokes on road safety signs. The feds aren’t laughing.

New Jersey had a message for drivers who might be thinking of hitting the road while under the influence of marijuana: “We’ll be blunt/Don’t drive high.” Another tried to protect woodlands: “Hold on to your Butts/Help prevent Forest Fires.”

The state was engaging in what is all but tradition for transportation agencies looking to spice up their roadside safety messages with jokes and pop culture references. One researcher gathered more than 350 examples of the messages from 12 states in 2020. But late last year, the Federal Highway Administration responded to New Jersey’s efforts at humor with a leaden warning, asking that it “cease and desist.”