Brown the ground beef and onion then drain. Replace in pan and add taco seasoning and water as per package directions. Remove from heat and cool for 30 minutes.
Layer 1/2 of the meat, 1/2 the sliced olives, 1/4 head shredded lettuce, 1/2 the cheese and 1/2 cup corn. Repeat the layering stopping with the layer of cheese.
Bake for 45 minutes at 350°