Sum 41 has 2 guitarists! I have only tabbed out
the main guitarist part. The other part isn't
as critical as this one.
For this tab it's in dropped D tuning. It doesn't
have to be at all but I find it easier to play
this way.

Intro: (0:00)
[E -------------------
B -------------------
G -----7-7-------77-- } x6
D -7-X-7-7-5-5-X-77--
A -7-X-5-5-5-5-X-55--
D -7-X-----5-5-X-----]
(0:15) (Just play that note a lot)
[E --------------------
B --------------------
G --------------------
D --------------------
A --------------------
D -7777777777777777---]
(0:23) Just after "Was happiness a fad?"
[E -----------
B -----------
G -----------
D -4-5-7-7---
A -4-5-7-7---
D -4-5-7-7---]
(0:26) ("…found…")
[E ------------------
B ------------------
G ------------------
D -5--4-5--4-4--2-2-
A -5--4-5--4-4--2-2-
D -5--4-5--4-4--2-2-]
(0:31) Just after "It might not be so bad"
[E -----------
B -----------
G -----------
D -4-5-7-7---
A -4-5-7-7---
D -4-5-7-7---]
(0:35) ("…tragedy…")
[E ----------------------------
B ----------------------------
G ---------77777777--99999999-
D -5--4-5--77777777--99999999-
A -5--4-5--55555555--77777777-
D -5--4-5---------------------]
(0:39) (Chorus)
[E -------------------
B -------------------
G ---------777-------
D -777-55--777-222---
A -777-55--555-222---
D -777-55------222---]
(0:52)
[E -------------------
B -------------------
G -----7-7-------77--
D -7-X-7-7-5-5-X-77--
A -7-X-5-5-5-5-X-55--
D -7-X-----5-5-X-----]
(1:02) Palm mute this except
every 3rd stroke.
[E ------------------
B ------------------
G -------------777--
D -777-555-777-777--
A -777-555-777-555--
D -777-555-777------]
(1:21)
[E ---
B ---
G ---
D -2-
A -2-
D -2-]
(1:22) (Chorus) Hold the last chord
[E -------------------
B -------------------
G ---------777-------
D -777-55--777-222---
A -777-55--555-222---
D -777-55------222---]
(1:47)
[E -----
B -----
G -9--
D -9--
A -7--
D -----]
(1:53)
[E ---------------
B ---------------
G -7---8-9--9----
D -7-7-8-9---9---
A -5-7-6-7----9--
D ---7-----------]
(1:58) Play these chords some more
[E ---------------
B ---------------
G -7---8-9--9----
D -7-7-8-9---9-9-
A -5-7-6-7----9--
D ---7-----------]
(2:22) pm........
[E -----------------
B -----------------
G -999777722224444-
D -----------------
A -----------------
D -----------------]
(2:40) Hold last chord
[E -----------------
B -----------------
G -999-77-222-444--
D -999-77-222-444--
A -777-55-000-222--
D -----------------]