I just spiked a vegan's food a couple of hours ago
I can't believe you would do that. Why would you spike a vegan's food?
I don't care. I keep telling him that I would do it until he  stops trying to stop me from eating meat.
It's unethical and immoral to tamper with someone's food so that they will eat something they don't want. Make amends with the people you victimized and try to get their forgiveness so you can move on.
I don't give a fuck if they eat something they don't want
A vegan doesn't believe in eating animals, so if you've put anything made from animals in their food you should apologize. It's wrong to do something so cruel to someone, and it could even make them sick.