... could have been a secret code.
I can just see a man in a trench-coat, turned-up collar, trilby pulled down over his eyes, sidling up to another man in a smoky bar and saying, 'Ze only free cheese is in ze mousetrap.'
The man at the bar replies, 'Zanzibar is 'ot at siss time of year.'
They both glance quickly around before a brown envelope exchanges hands and trench-coat man leaves.
I'm surprised Eddy Wotsit didn't pick up on it.