It could be one of several problems. Horses use certain behaviours when bored or unhappy or both. This may be your horse trying to tell you he would rather be doing something else. It may be he has sensitive skin and the grooming may be a little 'rough' for this horse. Try a lighter, softer brush, such as a face brush instead of a dandy, mud or stiff brush, and try a lighter hand while grooming. Remember to go easy on the face, legs and belly (sensitive and ticklish).
They will lay on the ground and kick up
Yeah they can they could kick you to death if they were wild or poorly trained or just plain spooked if you were on the ground or underneath the horse.
That depends on the type of horse
you kick the side of the horse and get it use to that
It bit my grandmother.
you have to kick your heels into the sided of the horse.
Yes they do kick back their legs like a horse does to protect themeselves.
Yes. If you think about it, all a bruise is is minor internal bleeding, or occasionally major. So, you would definitelyget internal bleeding from a light horse kick, although it may not be too major. However, if a hard horse kick can break bones, any kick from a horse is going to do significant damage to your body.
you kick him in the but
You seem to have some bad information, because a horse can kick out in all directions. Belive me, i know, I have been working, and training with horses for 10 years.
Gumby
An angry horse will put his ears far back on his head, almost flat. His eyes will roll and he will often shake his head violently up and down. He will also swish his tail back and forth, meaning that he is irritated or angry. Sometimes a horse will rest one back hoof tensly on the ground and stretched back -- if this is the case, DO NOT go behind the horse, as he may be ready to kick and a horse kick to the head can be dangerous or even fatal. If a horse is in his stall, he will often have many of the same motions and movements, but you should be more careful in a stall given the limited amount of space and the unpredictability of a really angry horse. If a horse is out in pasture, he will often run, buck (or kick out), rush you, along with the other signs that he is mad.