Put just ½ inch of water in a saucepan.  Add 2 tablespoons Old Bay Seasoning or other shrimp boil seasoning and a splash (about 2 tablespoons) of white or cider  vinegar.

Bring the water and spices to a full rolling boil over high heat.

Add up to one pound of medium shrimp, cover and bring back to a full rolling boil.

The instant the water starts boiling, turn fire down to low and begin timing 2 minutes very exactly.

After two minutes, turn the stove off or remove the pan from the stove if you're using an electric stove.

Drain water from shrimp.  There should be a lot of the spices still sticking to the shrimp.

You can either serve the shrimp immediately, or put it in the refrigerator to chill for a cold meal later.