Taken directly from the name of the main character of Diagnosis Murder, the act of doing a 'Doctor Sloan' involves solving, or helping to solve, a problem using information that by all accounts SHOULDN'T be useful at that point. Could also be described as a fluke
of genius in unlikely circumstances.
Person A: "Fat Fuck Freddy has gone to the chinese takeaway without me and left 10 minutes ago. We'll never catch him now."
Person B: "Doesn't he usually order a number 116 without prawns?"
Person A: "Maybe. What's your point?"
Person B: "He never has more than a fiver
on him, so he'll have waddled to the cashpoint first. We'll catch him there!"
Person A: "You sir, just pulled a Doctor Sloan"