This a lip oscillation coupled with a 'wob wob' dubstep sound popularized by Reeps One. It's extremely useful in dubstep and drum and bass routines in particular, and once you get the hang of it, it's quite easy to do.
Standard Beatbox Notation (SBN)
{ BBw }
How it's done
- Learn the lip oscillation by tightening the left and right ends of your mouth create a tight vibration of the lips
- While doing a lip oscillation push your tongue forward to get a "wob" sound
- Lather, rinse, and repeat
For the alternative sound, do the above to the side of your mouth without using air from your lungs. You can hum in falsetto doing this too.