Below is a small excerpt from the article in the Sun.
State law allows the MVA to deny tags that have a scatological or sexual meaning; use curse words, epithets or obscenities; carry a “fraudulent or deceptive purpose” (FBI and CIA are banned); refer to illegal acts (sorry, no HEROIN or KILLALL) or convey messages about a group’s race, ethnicity, religion, sexual orientation or disability.
Just being offensive to someone isn’t enough, [MVA spokesman Philip Dacey] says. That’s why SUX2BU joined the ranks of Maryland’s 88,000 approved vanity tags. “It seems like it’s more of a statement, just a personal view of the world,” he says, adding that employees use judgment in “gray areas.”
What’s interesting is that the plate shown above is permitted in Maryland. The person who owns this “CWBYSUK” license plate is likely a Redskins fan. I don’t think a Ravens fan would waste the money on insulting the Cowboys when they could insult the Steelers instead.