1. Seizure or epilepsy (http://www.epilepsy.com/).
A link about the disease is provided in case you don't know what it means. :)
Whenever it happens to a person, some people who're wallowed in ignorance and superstition might think he is bewitched. Wtf! Epilepsy is actually a common chronic neurological disorder, but not anything without adequate foundation. I never knew there're people who think in such a funny way until my cousin included "X hantu" in his slide yesterday.
There's something very simple you can do when it happens at nowhere. When it's in the middle of the road, make sure you get someone to stop the cars (you have to ensure your safety first before you safe the casualty), and bring the casualty to somewhere safer. Move away everything around the casualty such as tables, chairs, and et cetera, to avoid him from being injured.
Do not put anything into his mouth or else, he may choke by his vomit and suffocate to death, or he may have pneumonia by swallowing his vomit into his lungs; do not enforce him to straighten his four limbs; do not put your finger into his mouth as if you're so great unless if you want to lose your finger; do not enforce him to open his mouth; turn him to either left side or right side and wait until he is done. If he vomits, and if possible, you may try to use your finger or something else to make the vomit out of his mouth.
Going to the hospital is still a must for further checkup, though. Just so you know there're always so many busybodies around no matter what happens, you may ask one of them to call for ambulance.
There're some examples of how it would be when it happens.
It can be happened in different ways, and these are the only two.
2. Calling for ambulance.
Many people do not know that there's no either 991 or 994 anymore. Some of them even think there's such number 911. Wtf! Only 999 would work, and if you're using mobile phone, dial 112 or else, you wouldn't be able to call for help. Some people might be able to dial 999 with their mobile phones but, instead of wasting your time to try it out, I prefer calling 112 because it can be dialed even if there's no signal at all, such as forest.
You may try to dial it now, but I will never be responsible for anything happens. :P
3. Nose bleeding.
What you can do when someone is having nose bleeding? Ask him to raise his head? NOOO! Instead, you have to ask him to lower his head, and in the meantime, ask him to pinch his nose – the place under the bridge of his nose. If it bleeds for a very long time, please send him to the hospital.
The treatment above is just for the common situations. It wouldn't work well if the casualty cracks his nose bone; send him to the hospital as soon as possible. I guess you don't need me to do any more explanation about it, do you?
Those are the only three of them among the many misunderstandings that I would like to tell. May I know what else would you like to know? I would really love to answer you if I know.
I'm tired now. XD