Re: "two monitors plugged into each other, a USB mouse plugged in to an ethernet port"
"Can anyone explain how this could be physically achieved? I'm genuinely stumped."
The USB mouse plugged into the ethernet port is a piece of cake. When I set my laptop up in a particularl location, it's positioned such that I plug things in by feel - and USB stuff will plug very easily into an ethernet port.
The monitors - as someone upthread suggested, possibly two male ends to a VGA cable. In fact, depending how recent this was, that may very well be right - the connection at both ends is the same these days. (I had to unplug this very monitor to double check because I wasn't entirely sure). The same is obviously true of HDMI.