Okay, here it is:  Riff Tab for "Is It Luck?" by Primus.
Note: I didn't figure this out.  It was in the August 1991 issue of Guitar
Player....

  e  s s  s s s s  s s s s  s s r     e  s s  s s s s  s s s s  s s r

-----Xh6-----------Xh5-------------|-----Xh7-----------Xh6---------------|
--X-------Xh7-Xh6------Xh6--Xh5----|--X-------Xh8-Xh7------Xh7--Xh6------|
-----------------------------------|-------------------------------------|
-----------------------------------|-------------------------------------|

Just a reminder.....

X -- muted note
h -- hammer-on
e -- eighth note
s -- sixteenth note
r -- rest

A few notes Les gives:

"I play it on the 4-string.  I hold on to the whammy bar while I slap, which
gives it a real weird sound.  It's all on the D and G strings, and the second
bar is the same as the first, but up a half-step."

Another note: Les uses standard tuning, but instead of standard strings on his
4-string, he uses two A's and two G's to help out with his chords.

Have fun!  Later,
-Chris Carman
-cecarman@miav1.acs.muohio.edu