You hack ,mod, or get someone to do it for you.
Ray Gun
You can get it in the mystery box in Zombies.
yes
disco stick
The dragonuv is terrible
There is the Thundergun(Upgraded is Zeus Cannon) and a new freeze gun, a.k.a. death to zombies I don't know too much about it.
The is no MG 42 in Call of Duty Black Ops so it can not be used to kill zombies in zombie mode, but it is credited with leading to the development of the M60 machine gun which is available for Call of Duty Black Ops
Go to the "Mystery Box" and hope you get the Ray Gun
ray gun is only avalible in nazi zombies or in the mission little resistance after doing a glitch
Stick together if your playing online. Get the Raygun, it's a good gun. And also get the Thunder gun. You can find those two guns in mystery boxes. The related links have good tips if you go to the Map for Zombies in the call of duty black ops link or the Zombies mode related link
U just have to be a lucky sh*t and go to the box
you can't get it in multiplayer. you can only get it in zombies through the mystery box.