How disable startup sound mountain lion?

LOL. I read through the pages and there is no real solution. I don't understand why some people try to preach the Apple Way, saying this is for your sakes. It's like "you're holding it wrong".

I just hate that **** boot up noise. My colleague uses a MacPro and she always comes to the office later than me. Every **** time she turns on her mac, it makes that noise. Part of the problem is that she doesn't know about being considerate to others because she always let her phone on loud sound and never switch to vibration mode, and sometimes even sings Indian songs, but whatever.

My solution is to use a in-ear earphone and play music all the time when in the office. On my rMBP13, because I rarely reboot, I didn't really find it annoying until my colleague's MacPro boot up noise every day.

If it didn't make that sound how would you know she was better than you?