How to play b like korn?

Fieldy,as well as Munky tune down to B flat or A. That's how they get that weird clicking sound out of the b. When I slap and pop I try to hit the strings with the side of the top knuckle of my thumb. I actually have developed a callus there. I pop with either my ring or middle finger, depending on what sting I am popping. The key to developing good technique is to start slow. Don't speed up until you can get good tone at a slower speed. Start with slapping and popping octaves. If you don't know where they are, the octave of one note is 2 stings down and two frets down from each other. They are the same note put in a higher register. So if you slap an A on the 5th fret of the E string (standard tuning) you would pop the higher A on the 7th fret of the D string. Hope this helps.