Bring the lemons, onions, and Old Bay, and 3 quarts of water to a rolling boil.
Add the potatoes and let cook for 10 minutes. I check to make sure that they are getting tender. You still have some cooking time, but I get so mad when I under cook my potatoes.
Add the kielbasa.
Add the corn. Boil for 10 more minutes.
Finally, add the shrimp and cook for 3 minutes. The shrimp will be pink.
When the shrimp are cooked, strain the liquid from the pot. Put the boil into bowls.