"Screen sharing" on the command line?

If I am logged in to a remote server, and someone else is logged in to the same server, isn't there some way via the command line to let them "look over my shoulder"? Of course I could copy and paste my terminal scrollback buffer at intervals and dump it in a file in /tmp, and they could cat that file...that is close to what I'm talking about, though it wouldn't have color. This is very different from the typical meaning of "screen sharing" because it wouldn't involve any additional *network* traffic at all—just local resources. (You're both already logged in.) I have had *scores* of cases in just a few months where this would have been extremely useful. Is this possible? How can I do it?