The Texas Department of Motor Vehicles rejected more than 2,000 proposed personalized license plates last year.
The Star-Telegrapm reports that GOTWEED, CNN SUX, NOTRUMP AND NOBAMA were among those the agency's staff found in violation of approval guidelines.
Texas Administrative Code directs workers to look for inappropriate or "indecent" messages that may be misleading, vulgar, derogatory or reference illegal activities.
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Some license plates were rejected last year for misrepresenting law enforcement or government officials.
Allan Saxe is an associate political science professor at University of Texas at Arlington.
Saxe says personalized license plates can make drivers engage in road rage.
Department spokeswoman Wendy Cook says residents can appeal a vanity plate rejection.
She says the process takes about three months.