well first the horses are wild but also they spur them on the neck butt belly and pretty much anywhere they can reach so that they can irritate them as much as possible
A horse usually bucks because it is in pain, from it's teeth, back, feet or even if it is unhappy in it's own mind.
If you want to know how to make a horse buck then it's probably more than likely...
Any member of the equine family is known as a horse. Controversially, some people may wish to be gender specific, calling female equines horses and male equines stallions.