Latin phrase

Does anyone, besides Colin Dexter who used it in his book THE REMORSEFUL DAY, know the meaning og the Latin phrase: "Nunquam ubi sub ubi!"? Thank-you for any assistance.>>>

It's a Latin joke:
Numquam= never
ubi= where
sub= under

So when it's translated and sounded out, you say "Never wear underwear." Get it? Another variation is "Semper ubi sub ubi", meaning "Always wear underwear".