Me and my friends thought about doing some of these just to spice up zombies a bit, and have a couple laughs. We have been tossing around a few ideas such as seeing how far we could get playing the entire game crouched. We know it wouldn't be far, but thats not the point lol. It would require WAY more teamwork, and a whole new tactic rather than the traditional "run a loop" strategy.
Other ideas we had were
Shit weapons ONLY after round 10... Snipers, China Lake, Law, Spectre, M14, Olympia, HS10, etc..
Open 1 door every 5 rounds only (earliest you would get to the stage would be round 20).
Wall guns ONLY, no nades, claymores, knife, traps, etc...