I think I'm going to call out of work tomorrow.
Is there a reason why you don't want to go to work?
There's so much downtime at work, and I hate waiting for nothing.
That would be a very irresponsible choice. You will be reprimanded and will probably have a pay cut if you will not go to work without any advance notice. I would recommend you schedule a vacation time with your company so that it would be not taken against you.
Nah, I'm going to skip work anyway.
If people find out that you're skipping work, you may get in trouble. Instead of missing a workday for no reason, maybe you should talk to your boss about finding more to do in your downtime.