Can I conduct psychology research involving my restaurant customers without their explicit consent? I will be working as a waiter to make extra money, but I am also an ardent academic. I want to know if I can make audio and/or visual recordings of interactions with customers without having them sign some sort of waiver. Thus I won't necessarily have the names of participants. 

Can I later publish some papers without actual evidence other then someone listening to the tapes and concluding they are not all me pretending to do different voices?  It's in the interest of social psychology - will anybody consider this too invasive without permission? And is it less invasive and acceptable if i just try and conduct research on game theory (e.g., possibly trying to manipulate purchases between two customers as competitive relations)? Will it just be considered anonymous contribution, or am I soliciting information while withholding my actual objectives during interaction? 

I have no ethics committee monitoring me.

There are 3 days before I start my job.
What does your advisor thinks of that? 
What does your ethics committee thinks of that?

Because, as far as I know, every and all experiments that remotely involve humans need to be approved by an ethics committee. 

I'm from computer science but I had a few experiments involving people and that is usually the rule...

And remember, each country has its own set of laws, make sure you know yours!

Apart from that, my first impression was "bad idea". Even if it is, by some weird loophole, legal, it is not very ethical, at least IMHO...