you only can in two maps ascension and call of the dead...how you do this in ascension is you have got four of five perks and you get through the monkey round without a single monkey touching any perk and you get a free perk with the max ammo at the end.
in call of the dead what you do is buy four perks then you get a power weapon from the mystery box and you keep using the power weapon on George Romero and kill him with it (it will take a lot of ammo) then when he "dies" or gets sick of getting shot and runs away for two rounds he will drop a perk and a deathmachine (wunderwaffe dg2 if you've done the stand in achievement) and you will get a random fifth perk yuou can do this to get seven perks in call of the dead since there are seven perks.
hope this helped :D
8
You obtain different perks through stashing collections. Considering there aren't as many perks as collections, I assume it is a random gift.
Some of the Perks can be found under the related links although you do have to scroll down to the section
4
When you die in Zombies, you do not keep your perks.
PHD Flopper and Stamin-up
it depend sif your playing black ops zombies or world at war zombies black op zombies has stamin up double tap and PhD flopper regular world at war zombies has speed cola jugger nog and quick revive
Good Perks, good weapon combinations, good tactics, and a place to run to if you get swarmed.
I got better at zombies by playing often and watching YouTube videos, but I would recommend buying perks, learning how to "train" zombies, using Pack-A-Punch/traps/mystery box to your advantage.
Quick revive, juggernog or juggernaut, Speed Cola, and Double tap.
finding Death Cards unlocks certain "Perks" in online gameplay. Similar to the Halo 3 skulls (If you know what I'm talking about.)
you can only have 5 perks in cod black ops but there are 6 to choose from double tap (macks u shoot faster), quick revive, mule kick ( you get 3 guns ),speed cola , juggernog, , and pack a punch upgrades ur gun this only is for the map kino der toten