I tried using hot sauce to train my dog to stop begging. He’d beg while I was eating, I’d put hot sauce on whatever, and let him eat it, in the hope that he’d associate his begging with “the burn”.
It backfired, and he loves the stuff. Go figure.
That said, this “parent” is a sadistic jerk.
I never even had to do that with my dog! Just push his head away a few time (big dog) and he got it. He’d sit and wait for me to be done then I’d give him what I had left. He soon learned that I would.