In the early 70s, Top 40 KKUA in Honolulu branded itself as "The Big Six-Nine" - I assume because "The Big 69" would have other implications. Not sure why they didn't consider "The "Mighty 690."
I saw my still favorite vanity license plate in the mid 70s on a huge Lincoln Town Car in the North Beach neighborhood of San Francisco. I may have the spelling wrong, but it was "A FUNGOO," which is a popular profanity in Italian. I've read that the DMV censors anything improper or profane - even checking plate requests in the mirror to make sure they're not inappropriate backwards. So how that slipped past the censor, one can only speculate.