Public Safety

Here's a funny story for you:
I went to the hospital for a chest x-ray today, and while I was waiting, a kid (I'd guess 15?) and his mom came in. I noticed he had a graze on his elbow and it was really swollen.
him to his Mom: I bet the x-ray will show 2 hairline cracks
me: were you skateboarding?
his mom: ha! See???
him: no, I was riding my bmx. At the skateboard park.
me: were you wearing a helmet?
his mom: HA! see? (and to me): thank you!
him: well, no
me: come over here so I can kick your ass
He got up, came over to me, and presented his ass. I KICKED IT!
his mom: HA! See? Thank you!

I then proceeded to tell him a bunch of stories about ski patrolling and nasty head injuries and wearing helmets. He was really polite and attentive, but I don`t know if I swayed him.