A customer comes into my key shop and tells me that he has locked his keys in the car.
Since this was in the 70's I say, "No problem, I can pop it open for five bucks," and he agrees.
Because I have done this a thousand times it takes me about 30 seconds to open the door and because I have done this a thousand times I reach in and grab his keys before he can. "Five bucks please."
He says, "No way, 30 seconds work is not worth $5, here is a dollar."
Me: "We agreed on five bucks."
Him: "Not going to happen, take the dollar or nothing."
Me: "Not a problem, 'nothing' it is."
Then I toss his keys on the front seat, hit the locking pin, close the door, and start to walk away.
He says, "Wait, you can't do that!"
Me: "I looks like I just did."
Him: "All right asshole here is the 5 bucks."
Then I say, "Well now you want me to open the car twice, so it is now ten bucks, in advance please."
--The Key Oracle