Paddy goes to the patent office, having invented a new mouse trap, It consists of a ramp with a razor blade at the top, set at right angles. Below the drop is a piece of cheese.
Patent officer: “How does it work then?”
Paddy: “It’s quite straightforward, The mouse walks up the ramp. When he leans over to get the cheese his neck goes onto the razor blade and it slits his throat”.
Patent officer: “Stupid git! There wouldn’t be nearly enough pressure to slit it’s throat. Get out of my office and don’t come back until you’ve perfected it”.
After months of head scratching Paddy makes a single but vital modification: he removes the cheese. He proudly returns to the patent office and puts the trap on the desk.
Patent officer: “OK, smart boy, enlighten me”.
Paddy: “Simple. Mouse walks up the ramp, leans over onto the razor blade and slits his throat…”
Patent officer: “But that’s exactly the same as before!”
Paddy: “No, no. This time he moves his head from side to side saying ’”where’s the bloody cheese ?”