Still, if the team is not really tight, this kind of prank is dangerous for the team. I can see the situation deteriorate pretty fast. If he was chief of security or something, I'd understand that. I understand the manager too, but a co-worker? No.

That said, I use padlock[1] on my laptop, especially in 'hostile' environments and I'm pretty happy with it.

[1] http://mizage.com/padlock/