"BLASPHEMY!"
or
"Plot hole time folks! thank you for testing my new state of the art hologram/robot lookalike,
I'm on vacation somewhere sunny right now, please leave a message after the tone"
except there is no tone, and you are left in my boss room for all eternity waiting for the tone so you can complete your quest MUAHAHAHAHA.
or
"NOOOOOO, not my [insert item of supreme power here] please don't take my [insert item of supreme power here] NOOOOOOOOOOOOOOOO!" (then when PC takes it) "HAH, its cursed, *****." /die