I didnt think much of it till my little brother showed me a vid of himself being slapped in the face by a mate. He seemed to think it was hilarious, i would have cracked him one back.
Then he showed me one of a girl who some kids (not known to me bro) tripped over and just laughed at her. She looked well sad and just got up and walked away.
Teens seem to find it well amusing. Well wrong imho. If it floats your boat then slap your consenting mates for a laugh but not innocents.