A keylogger on the back of the boss' computer? A hardware VPN backdoor to the company's network? Oh maybe bring a flash drive full of malware and viruses and just drop it in the break room?
Please don't do this, you will be tried and probably end up in prison. There must better ways to be petty that won't give you problems with police and judicial system.
I was involved as a witness in two cases like this, not only it creates problem for you but a lot of other people as well.
You didn't hear this from me, but I hear a lot of cubicle corners have removable caps that can make a great storage place for all kinds of interesting things.
Well if you were using that malware to gain remote access to a system or to exfil data, then that would be clear cut unauthorised access of a computer / network.
But if the malware wasnt giving you data and access, then it would probably be acting with intent to damage a computer system or network.
You might argue that the fault lies on the person who picked it up and plugged it in, but by that logic, it wouldn't be illegal to distribute rat poison at a dog park or to set rabbit traps in a playground.