The funniest prank I ever played on someone is....

 I once had this girl convinced that I was a witch and that I flew on a broom every night. 

In the back of my closet was a secret door to my magick room where I did all of my 

magick spells and stuff.

I couldn't show the room to her because normal people couldn't see it, 
only witches can see the magick room. 
She asked me to fly by her room and wave to her so I said I'd try.

The next morning she came running into my bedroom and thanked me for flying by 
her bedroom window and asked me if I saw her waving to me. 
I just stood there looking at her smiling.. 
I had no clue where this girl even lived let alone where her bedroom window was! LOL