Chester,
As others have said, the best way to do this is with a clamp on ammeter and one of the units that you insert between the plug and receptacle that separates the hot and neutral and lets you run the clamp around a single conductor.
However your question itself indicates a basic misunderstanding of voltage and current. You seem to be suggesting that you could pull the plug out just a little bit, and place your meter leads against the bare blades of the plug. Is this what you are suggesting?
If so, then you will not be able to use this technique to measure current. You would be able to measure voltage this way; but if you tried this with your meter on the current setting then you would be short circuiting the supply through your meter and sparks would fly.
Voltage is measured between two locations, using a high resistance meter connected between those locations. Current is a measure of the rate of charge flow past a single location, and is measured using a very low resistance meter 'inserted in the path', or by measuring the magnetic field around a conductor.
-Jon
