I'm planning to prepare a cake using a chocolate laxative.
Oh no, that sounds harmful. Why are you going to do that?
I want to pay this guy back for being a jerk to me.
Getting revenge may sound good at first, but it's really not a good idea. It's not okay to try to harm someone. What if he decides to harm you back, or press charges against you?
I'm probably going to get my revenge through my cake.
I do not suggest that you do as they can get really sick eating your cake and then they would be put to a hospital and you will be responsible for their medical bills. I understand you were probably hurt with that person, but retaliating is not the best way to deal with healing. I hope you just move on and just move away from people who has done you harm.