Happened to me a number of years ago. I was posted at a quiet procedural station.
Pilot: first contact "TWR.......... er... Reportmy postion"
Me: "Last caller say your callsign"
Pilot: "Er ..ABC, request my position"
I explained that as a procedural staion I was unable to see him on radar however I'd give the nearby sector a call and see if they could and get back to him.
Me: "ABC, adjacent sector advises they have to on radar 25nm SE of my field, 5 500feet... Do you need some assistance?"
Pilot: "copied..."
DEAD SILENCE
Pilot: "TWR, report YOUR position!"
I had to bite my tongue...