My teacher caught me smoking off school grounds and SPANKED me?!?

Yesterday after school (I go to a public school) I was smoking in the parking lot of a grocery store (I'm 18 and it's legal) when my teacher came out of nowhere and started lecturing me about how smoking is so bad etc etc and then started hitting my butt really hard with her hand. The whole time she was saying how "this is for your own good" and stuff...wth?!