Do you wash your mellons before you cut them? You should. Most of the mellons like cantaloupe come from places like Mexico and South America. These places commonly use human waste as fertilizer. It never actually gets washed off before you buy it. So, when you slice through it with your knife, the knife pulls any contamination with it into the mellon. The part that you eat. This can make you very very sick. Just refer to the link above. If you search you would likely find a lot more examples. I just did a super quick search to find this link. I remember hearing a few years ago about something similar with Mexican strawberries making people sick and dieing.