In a large bucket or cooler, place live crawfish, 3 cups salt, and water to cover. Let stand for 30 minutes, discarding any crawfish that float to the top (which indicates crawfish are dead). Rinse crawfish thoroughly using cold water.
In a large outdoor 60-gallon pot with a crawfish basket, place 2 bags Slap Ya Mama Cajun Seafood Boil, lemons(squeezing juices), and remaining 3 cups salt. Fill halfway with water, and bring to a boil over high heat on a heavy-duty outdoor burner. Add potatoes, corn, and garlic; bring to a boil. Reduce heat and simmer for 15 minutes.