Five cannibals get appointed as engineers in a defense company. During
the welcoming ceremony the boss says, "You're all part of our team now.
You can earn good money here, and you can go to the cafeteria for
something to eat. So please don't trouble any of the other employees".

The cannibals promised.

Four weeks later the boss returns and says, "You're all working very
hard, and I'm very satisfied with all of you. However, one of our janitors
has disappeared. Do any of you know what happened to him?"

The cannibals all shake their heads no.

After the boss has left, the leader of the cannibals says to the
others,"Which of you idiots ate the janitor?"

A hand raises hesitantly, to which the leader of the cannibals replies,
"You fool! For four weeks we've been eating Team Leaders, Supervisors and
Project Managers and no one noticed anything, and you have to go and eat the
janitor!"