Regarding the vanity plate on my motorcycle, “Bollox” (usually spelled “Bollocks”):

“Bollocks” is a word of Anglo-Saxon origin, meaning “testicles”. The word is often used figuratively in British English, as a noun to mean “nonsense”, an expletive following a minor accident or misfortune, or an adjective to mean “poor quality” or “useless”. Similarly, the common phrases “Bollocks to this!” or “That’s a load of old bollocks” generally indicate contempt for a certain task, subject or opinion. Conversely, the word also figures in idiomatic phrases such as “the dog’s bollocks” and “top bollock(s)”, which usually refer to something which is admired, approved of or well-respected.

It’s really quite versatile, perhaps more so than any American profanity, which also makes it difficult/tedious to explain when people ask.