Bounce - System of a down
Tab By Starky - aka Shadow Dragon
Now this isn't exact as the timing of the riffs shift a bit... but point you in the right direction.

Riff one

G
D
A
E 4 33 44 33 44 33 434
B

Riff 2

G
D
A
E 44 3 44 3 44 3 443... 33 7 33 7 33 7 33 7
B

G
D
A
E 33
B       1 - etc, etc


and thats about it... If you havn't got a 5 string, you can tune to the SOAD tuning of CGCF to get it.

Starky