Biggus D

I'm obviously coming into this discussion a bit late, but it needs to be said that this is NOT just happening because of mis-pressed buttons. You can strike your horse by just tapping Y. You'll even do it several times in a row if you're quick enough, and if you're behind your horse you'll slap its ass instead of punch it. After a moment or two, you'll come out of horse-beating mode and things will be normal again. I just can't for the life of me figure out how I get into that mode in the first place.