I want to leave my job without giving them notice
Seriously? Why would you leave without giving them notice?
I don't care about my job anymore and I think it's time to move on.
Even if you don't care about your job, it's wrong to just leave them abruptly. They need time to find a replacement for the job they were counting on you to do. If you want to quit you should consider giving them at least a week's notice first.
I don't really care. Plus I want to leave in a couple of hours anyways.
You should care because leaving a job early could damage your reputation pretty bad. You should just give them two weeks notice.