Fish

Give a man a fish, feed him for a day. Give a man a poisoned fish, not only will you feed him for a lifetime, you'll be rewarded with free housing and food for the rest of your life. The more poisonous fish you hand out, the higher the security of your new room. If you hand out enough, you'll even be recorded inside every single history book for you magnanimous deeds. You might even earn a personal meeting with Satan.