Easter eggs as IP protection in software

Question

I work in embedded software, and for some reason, management wants to hide an Easter egg as means of IP protection. They call it a watermark, and since our software interact with the video preview feed (the image displayed on a screen before you take a photo), they want me to implement a trigger which will react to some unusual video input (a video konami code like dark - bright - dark - bright - whatever). When this trigger fires, something strange happens (which is outside of the normal behavior of the software).

The goal is to check whether our software is included in a device. Does it sound like a good idea? I have many argument against this move:

• What if the konami code is too sensitive and user triggers it?
• Does this kind of watermark have any legal value?
• What if this "feature" is discovered by the client?
• The performance penalty should be very small, since the soft run on small devices.
• I am the one developping this trigger. If things go wrong, what is my responsibility?

What is your opinion about this method? I can't find a link, but I remember seeing an answer on this site suggesting that putting Easter eggs for protection purpose was a good idea. Has anyone tried it with good results?