Re: "Yes. I'm the decoy," I say, as the sound of a heavily loaded shredder...
"Tonight I'm the designated decoy."
While you might get away with that line when trapped in an elevator with the boss, saying it to a law enforcement officer may very well not be extremely wise. To put it lightly.
Even in the BOFH case, a non-incriminating line about decoys in general followed by an awkward silence to let it sink in (a process helped by the *kathump* *kathump* from the shredder) might have been more appropriate. And somewhat funnier.
Even something like "Nah, company's fine. Say, are you familiar with the concept of decoys?" *kathump* *kathump* *kathump*
But what do I know, I'm not familiar with the concept of destroying evidence in secret. Usually taking painstaking steps to ensure that the right names are on the right papers is usually enough to ensure that evidence will at the very least be overlooked. Or destroyed by somebody else.
When you can summon written evidence of approval from high up in the foodchain, Bob's your bitch.