All depends what terrain you are hunting. If you are hunting heavy brushor swampy areas and it only has a clear escape path and you are standing in it, it is going to charge you trying to cut you on the way out. Usually right between your legs swinging it's head side to side!

If you hunt open areas, chances are they will retreat in the opposite direction. Sometimes, even in open terrain, if you get to close to a Boss Hog, it will show you who's Boss!