Simulate OS X on Linux?

Hello There
I am attempting to assist my friend who is having a problem with his iMac.
It has both OS X and OS 9 installed, but I am not ( :-( ) a Mac user myself.
Knowing that both have Unix origins, I wondered if there was any way I could simlulate OS X on/in Linux.
This would help me get 'up to speed' and give me a better chance of being a help for my friend.
Regards
Echo

I do not believe you can but you could always spend a few hours at an apple store getting familiar

Yeah... the easiest way would be to use a real one first. If his is functionable just fool around with it to get the hang of it. Also, if he has a problem on his mac and u dont really do macs...why cant he just go to the store to have it checked out?