I believe you mean what could be the worst thing they could do to you if they tricked you. Some people believe in genies, some don't, and some think of them more along the lines of demons lacking the whole Aladdin version ability to grant 3 wishes. The old belief around tricking you in relation to granting a wish is twisting the meaning of your words. Such as if you wished to be rich they could give you stolen money resulting in jail time for you, kill a family member who's will your in, etc... The belief is they grant your wish just as you asked, but it's open for their interpretation as to how it is granted. A simple wish in theory could be disastrous. Pretty much anything you say could have a loophole this being could exploit. As for the more realistic energy beings known as djinn I don't know much about them except there are different types of djinn. The best the thing I can say is if you can't answer the question your not experienced enough to attempt summoning such a being. Look up the correct term "Djinn" and learn more about them and magick in general before attempting such a feat as I have to assume this post is related to the desire to summon one.