How to get back at a boy at school?

This boy at my scool has been bugging and pranking me for ages!The most recent being on friday , we had the same second break detention ( basically a detention at our main break ) with the most of a teacher. we went to the detention the the teacher wasnt at school that day. The monday afterwards i forgot , im sorry but im very very forgetful , and the day afer i asked the boy should we go to the detention today. He said no , the teachers not in today either. i thought all along he forgot on monday too because he said he had. Turns out that the teacher was their and he DID go to the detention on monday and just got me in more trouble. now im going to have to stay for hours after school with a teacher shouting at me and working me like a mule. To add injury to insult this is the type of teacher who holds grudges. Every R.E lesson from now on will be him basically bullying me. Anyway about this boy. his name is george and hes a small , smart , arrogant , selfish , annoying ***. You never know when hes being serious or sarcastic or wen hes taking the piss out of you. He always make you feel like a complete dumb. Hes smart , top set in basically every subject , a teachers pet. I want to get back at him for all the things hes done to me , like a good prank or something. sorry its such a long winded question. thanks.