The EvoAImessages on signs that some drivers see while commuting across the U.S. can range from pop culture references to humor.

Phrases like "Wearing your seat belt is so fetch" is a nod to the "Mean Girls" movie, and "Cut off? Don't get bad blood. Shake it off" is a reference to several Taylor Swift songs.

However, the Federal Highway Safety Administration is pumping the brakes on this trend. Their newly issued guidelines say "States should avoid the use of humor and pop culture references because it may confuse or distract drivers." 

The recommendation is not sitting well in states like Arizona, where the Department of Transportation has been using humor on its 300-plus message boards since 2015.

"Those friendly, humorous reminders, I believe have a very positive impact overall on the millions of people we have on the roads every day," said State Rep. David Cook of Arizona, who chairs the transportation committee.

The state's approach to traffic safety messaging includes an annual contest for submitting fun safety messages. Last year, it received 3,700 entries. Arizona's governor previously vetoed a measure that aimed to dampen sign-board humor.

In Wisconsin, Jon Riemann spent several years coming up with memorable traffic safety messages. He said he finds the federal guidelines "unfortunate." 

"I think that there is a great opportunity to message to the public, and, you know, to put out safety messages, to try to tie in pop culture or tie in things that are happening in your community," said Riemann.

Studies on the effectiveness of humorous signs are mixed. While one study found they command more attention, another suggested that people might not get the joke. However, the general public seems to appreciate the lighthearted approach. 

The debate over how best to convey safety messages on the roads is now written in lights, with the new federal guidelines set to take effect in 2026. 

Kris Van Cleave

Kris Van Cleave is CBS News' senior transportation and national correspondent based in Phoenix.

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