So several ideas in that case:
Sneeze over the food very loud and nasty
Lick the burger and claim yours

If not feeling savage, hand him the burger and get another one or two immediately after

Maybe it’s because I have been in this situation before that I know exactly how to act haha usually a resounding NOH solves it lol. My cousins and uncles are notorious for trying to pull this shit on other people. I know how these bastards act step by step 😅