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"
by Ivor Alias May 11, 2009
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