#3. Put a laxative in his coffee cup.
I wouldn't do this. A few kids did this a month ago at my school to 4 teachers. They got caught and were expelled. Me, along with a couple dozen other kids knew about it but didn;t fess up, so we all got suspended. One of the teachers is filing a lawsuit against the kids because of it, and it is a criminal offense. I don't recommend doing that.