Cho'gath Q hit box
Just about anybody that owns/has laned against Cho'gath knows that Cho'gath's Q hitbox is smaller then the green circle. If somebody doesn't move and you place a Q where they are inside but at the edge of the green circle, they wont get touched. It's so annoying to think I'm getting a kill and somebody just casually walks into it and lives. Don't worry, I'm not a stupid person that sees them walk into the hitbox right after the spikes have launched because I know that doesn't work.