Don't Mess with Texas” takes on a whole new meaning as the state cracks down on violators of it's trademarked, and most popular catch phrase.

What started as an anti-littering campaign nearly 30 years ago has become what some call it the most successful marketing campaign ever.

TxDOT's Veronica Beyer says the trademark has been challenged on everything from books to belt buckles.

“We know Texans are a proud bunch, and we're happy 'Don't Mess with Texas' has really become an iconic slogan in our great state,” Beyer tells KTRH News.  “We just have to make sure it's intended anti-litter meaning is protected and not diluted.”

Marketing guru Tim McClure of GSD&M is one of the men who helped come up with the famous phrase.

“I'm kind of wishing I had reaped those benefits,” says McClure.  “If I had a nickel for every time those words 'Don't Mess with Texas' have been spoken, I'd probably be talking to you from the Bahamas right now.”

WATCH: Don't mess with "Don't Mess With Texas"

“I always thought it sort of belonged to the people of Texas, but that's the state's prerogative,” he says.  “I'm glad just the phrase itself is now making money to help pay for the rather large cost of keeping our state clean.”

Texas also owns the rights to “The Alamo” and fought a San Antonio bar owner who wanted to print “I Can't Remember the Alamo” on t-shirts, mugs and other items.

“You have to carefully monitor the use of your mark to ensure you don't ultimately lose your right, and to ensure you get paid royalties,” says Jacqueline Lipton, co-director of the University of Houston's Institute for Intellectual Property and Information Law.