Girls, plz help me out with this!?

let's say your 14-year-old bro is getting circumcised on monday (medical reasons, ouch, lol) and you want to play a little prank on him. he did the same thing to you when you had a surgery last year. so let's say you want to get him to believe that he'll be awake and won't be able to have anesthesia for it. how would you pull off the prank? like, if your mom was OK with it, would you get her involved? how would you pull it off? of course, i'll tell him RIGHT AWAY that i'm joking. best idea gets 10 pts!!!