B.C.
Different kids do different things to "get even" with their parents for telling to do things they don't want to do. My kids chose to jump up and down and scream and cry. I made them jump up and down and scream and cry long after they wanted to stop. I made them do it until they were really, really, really wanting to stop. It stopped the tantrums. Sometimes they got swat for not continuing to jump up and down and scream. It caused them to stop.
You can't make a kid throw up. But you can call the people that say the child is perfect and tell them to clean up after the perfect child. If dad is the one that says the child is perfect, let him clean up the mess. I would, however make sure the child is clean and not sick. I would wash his face very carefully, probably several times and I would certainly put him in the shower or place him on a chair and wash his hair with a spray faucet at the sink (if you have one). I'd tell him that when he throws up he is speading germs and you must make sure he is clean and sanitary. I would make sure to tell him that you must wash the germs off his face and hair that wouldn't be there if he didn't throw up.
You can be the mom psychicologist and make sure his tantrums are rewarded with something he really doesn't like. Be sure to make him do what ever it was that he didn't want to do when he got mad and threw up. You have nothing to throw up on an empty stomache.
ETA: I just read the post by Barb K. She is correct about shocking them back to the real world. When my number 2 was about two or 2.5, he got mad about something and started to scream and cry. I let him scream and cry for about an hour. I told him to stop several times and he just ignored me and kept it up. I picked him up and tucked him under my arm, went to the frige and got the pitcher of cold water out and took him to the kitchen sink. When he saw what I was going to do, he immediately yelled, "No dad. No dad. I'll stop. I'll stop." I told him, "Then stop." He stopped and I put the water back in the frig. I told my wife and she later said it worked for her too. All she had to do was threaten the cold water and he would regain control and stop the tantrum.
Good luck to you and yours.