This came to me via certain reprobate, though eminently professional, staff at a particular Soho hostelry of my acquaintance. It is, allegedly, popular, towards the end of the night amongst bartenders, as a pick-me-up to help make it through the last hour. I reckon that would do the trick.
Prepare a shot of ice cold vodka. If the bottle has not been kept in the freezer, quickly shake it with ice, but not for very long or it will become diluted. You don’t want that, do you now.
Lay out a slice of lemon. Sprinkle a teaspoon of freshly ground coffee on top followed by sugar to taste. Fold the slice in half, holding the two ends together, the fold facing forward. Knock back the vodka shot in one then bite into the folded lemon and suck.
Now back to work and take no prisoners.