Complete foolishness, but every region has its own customs and games. For example, in North Africa, there is the 'sheep fight,' where they bring two rams to butt heads against each other, and the winner earns money. and some people even bet on the winner..
What doesn't make sensw to you could be sensible to another person same thing goes to our culture and tradition, there are so many things that people enjoy in their culture that others detest but you should not condem people for what they enjoy especially when they have been doing it for a long time. Cock fighting, butt fighting and other things are what people consider as fun and source of income to them even when we don't like it we should learn to respect their decisions and likeness. Imagine people Money legitimately when two cocks or butt fights each other it's sounds crazy but money is involved so it's fun.