What happens when you sit out?

A. In a non-tournament setting, you can sit out for a few minutes and not lose any money. After a time, if you sit out for too long, your funds will be taken off the table, credited to your account, and when you come back to your screen, you'll find that you're just in the lobby again.

However, in a tournament, if you sit out, your blinds will still be taken and your chips will gradually diminish. Even if you're in the big blind and no one raises, you cannot win the hand, even if it gets checked down. So you should wait for the scheduled breaks if you're making a bathroom trip or want to grab a sandwich out of the 'fridge.