[winrid]

The problem is the manager would probably start with "did you have a pizza stolen?" without mentioning HR

[psd1]

The stolen item needs to slightly vary in each telling. Catch a mole 101.

[greedo]

They'll have to call it the "Pizza Trap" instead of the Canary Trap...

[akomtu]

From this question alone you could figure who's trying to backstab you.