A third incident saw a young boy being tricked by friends into doing the Skullbreaker, which knocked him unconscious and caused head injuries.
"It never ceases to amaze me the stupidity of people," cyber safety expert Susan McLean told Yahoo News Australia.
"Parents need to be aware of what their kids are doing and they need to have conversations with them about what's acceptable behaviour on the internet."
McLean urges those using social media to not participate in activities "that are likely going to cause you or someone else harm".
"All you can do is have conversations with your children about their behaviour both on and offline – that's your job as a parent, to make sure your children travel safely through life to the best of your ability."