Just tell him how much of a massive jackass he is. I did that once, in a fun way.
We had to prepare christmas dinners once for school.
I was grouped with 2 of my friends and some girl I really hated.
So when she told me to wait until it was done, I snuck up to her room, got almost all of her hair cream stuff out of the tube, then replaced it with glue, food dye and some stinky medicine I used to take when I was younger.
And when she came to school that evening she had to wear a hat all the time. That was the best evening of my whole life, because I laughed harder than ever.
I felt pathetic for actually plotting that out correctly for a whole week, just for a prank.
But having revenge is sweet.
She "stole" my friends from me by making them popular, knowing they wouldn't hang out with me anymore.
This was the ultimate way to show her how much of a pathetic child she was.
