Get a pot of water and put into it some garlic cloves (just smashed is fine), a couple stalks of celery (broken in half), some spring onions, a can of beer if you are old enough, a palmful of whole peppercorns, a few whole cloves. Bring water to a boil, dump in shrimp, remove as soon as they start to turn pink. This shouldn't take no more than 2 - 2 1/2 minutes depending on the size.
OR...
You can place in a casserole dish. Melt some butter, lemon juice, chunked garlic, Worcestershire, ground red pepper or your favorite hot sauce, pour over shrimp and bake at 400 degrees F. for 20 - 25 minutes.