I had a job like that. It was a public secret that the night shift people were there just in case someone called - we generally got 3-5 calls per shift and there were something like 7 people. I didn't really use Reddit at the time, but they didn't block Netflix or Hulu so I (and most of the others) just watched those. I read a lot of books, too. Some people slept through their entire shifts. I only fell asleep once, by accident; I was always too nervous I'd miss a call. One shift a co-worker and I just played Fluxx waiting for calls.

I was at that job for eighteen months. When I left, I was worried that I didn't know how to work anymore. I was well liked, sometimes even specifically requested, at my next job, though, so perhaps the time semi-off helped me.