Many MMA fighters LOVE to trash talk their opponents. They do it either to intimidate or just to mess with their opponents' heads. A recent example of this is Frank Mir trash talking Cheick Kongo. Mir followed up with his talk, but some fighters don't. It sure is hilarious to see a fighter make fun of/trash talk his opponent and then get KO'd in the first round.
That's why some fighters don't trash talk. It makes them look like a total idiot if they lose. Regardless of the consequences, some fighters trash talk anyway.
These are the top 10 worst trash talkers in MMA.
P.S. Since it is hard to put depth into this kind of talk, the explanations won't be that long.