Hidden trophies/achievements?

[dbgtz]

What are they? I need to know one of them and I can't find them anywhere. I have the "play zork" one and "break free from the chair" one. Gonna go for all the easier ones first :P

[crazed]

Same as xbox...

http://www.xbox360achievements.org/game/call-of-duty-black-ops/achievements/