- "I've felt anxious too"
Feeling anxious/stressed and having an anxiety disorder are two completely different things.
- "I feel down too sometimes"
Feeling sad and being depressed to the point where you want to end it are two different things as well.
- "Just get over it"
Sure, why not? All my mental issues are cured now! Thank you so much!
- "You know your thoughts are not real, right?"
Yes, I am aware that my delusions are not real, but it doesn't prevent me from thinking so when the time comes.
- "Nothing is wrong with you, all teenagers feel this way"
Oh, nothing is wrong with me? I AM CURED ONCE AGAIN! WE'LL SEE HOW THAT SAYING GOES WHEN I TURN 20!
- "It's just your hormones/It's puberty"
Cured. Again. No thanks to you. There's a fine line between mental illness and puberty.

Most of these I've heard from my parents. It really does not help whatsoever. There are many more I could list, but these aggravate me more than anything.