The guitar riff is quite simple
and it oscillates between strings (if there is such a thing).
The basic riff is:

E|----------------------------------------
B|----------------------------------------
G|----------------------------------------
D|----------------------------------------
A|-------------------------------------5--
E|--3---1---0---1--3---3-5-3-5-3-5-3-5----


There is also a part in the song where the riff changes, it goes unto a
different string like this:

E|----------------------------------------
B|----------------------------------------
G|----------------------------------------
D|-------------------------------------5--
A|--3---1---0---1--3---3-5-3-5-3-5-3-5----
E|----------------------------------------


There is also another part of the song where the riff goes on the D string,
which I will not get into at this time as you may see the point of this.
And that is basically it.

Screw
-----

When you screw up your eyes
When you screw up your face
When you throw out your arms
And keep changing your shape
Taste the taste in your mouth
Taste the taste on your tongue
On the film on your eyes of what I've become

What do I do when you screw up your eyes?
What do I do when you screw up your face?
What do I do
When you throw out your arms
Fall on the floor
And keep changing your shape?
Jump right into your mouth?
Jump around on your tongue?

And the film on your eyes of the way I've become
Makes me sick at the way that I try
Anything in the world
To impress that I'm doing this
Only for you