I witnessed this once years ago during the start of a class I was attending. Girl from the back gets up and starts walking towards the door, mumbling. She seemed off, so I stood up and asked if she was okay. She fell straight back and I tried to catch her but failed. She foamed at the mouth and started turning blue. I had no idea what to do. Medics show up and the class clears out, but I stayed because she basically half fallen on me. When she woke up she looked straight at me and said “hi.”