Rich guy buys a very expensive complex single having gained licence on simple trainer. Comes to us for differences training. "I'm already flying the new one with a friend, wink, wink, just want to get the sign off from yourselves", he sees fit to mention.
Not a good start.
I give him a thorough briefing on the specifics of our own model, quite different from his, and on the principles of prop/gear management. He is noticibly impatient during the breifing (knows all that already...) , takes an "important" call on his mobile, etc.
Eventually we go flying. I tell him for the first take off to follow through, I will be in control. He makes an exasperated sound. On the takeoff run at about 10 kts below recommended speed he suddenly hauls the wheel rearwards. Stall warner blaring the aircraft lumbers a few feet into the air and mushes along in ground effect. Wing drops. I shout I have control and we get airborne. He is virtually gibbering at this stage. For the rest of the lesson he is meekly compliant, and in the debrief when I ask him what the f*** he was doing he says oh, well that is the speed on my own aircraft.
I make it clear I don't want to fly with him again and we never see him again.