Paddy needed a piece of glass, so off he went to a glazier.
Glazier: “What size do you want?”
Paddy spread his hands, and said: “About this wide,” then spread his hands one above the other, and said: “And about this high.”
Glazier: “I need proper measurements, Paddy, otherwise it won’t fit.”
Paddy: “I’ll show you again,” and went through the hand-spreading routine again.
Glazier: “OK, Paddy, we’ll do it your way.” The glazier put his fingertips to Paddy’s fingertips, then marked the glass in both directions, and cut out a piece.
Glazier: “You can have this for free, Paddy, but I’ll bet you £50.00 that it won’t fit.”
Paddy: “You may as well give me the £50.00 now. I haven’t made the frame for it yet!”