I think I had a panic attack once, but it may have just been an actual fear.
It was the dead of winter, me and my friends were in a wooded area next to a highway and it had snowed the previous night. A lot.
And I don't wear very thick jackets. None of us do. So there we were, dead of winter, snow up to our shins, and nothing but hoodies and spring jackets as protection, smoking a blunt. Really good shit though. We finish, and I'm suddenly filled with the overwhelming feeling to go home. So we walked for what felt like hours to bus, and then waited another 20 minutes for bus, words can't explain the happiness I felt when it showed up. But by the time it did, I couldn't feel my legs. I got home and immediately went to my blanket and was shivering and cold the whole night. I think I may have been in danger of dying.