Janis Joplin & the Big Brother and the holding company. 
 
Riff I : 
(1st time) 
 
E|-3--1--3-------------------------------------------------------5-3---0-3-0- 
A|-----------2--3--4?5-4-5-------5--------5---3--2---2-2---------------- 
D|--------------------------------2------2--2---------------------------------- 
G|------------------------------------------------------------------------------ 
 
(2nd time) 
 
E|--3--1--3------------------------------------------------------ 
A|------------2--3-----5-4-5----------2-3-2------------------- 
D|-----------------------------------------------2-3-4-5--------- 
G|----------------------------------------------------------------- 
 
Riff II: 
(1st time) 
 
E|---------------------------------------------- 
A|--3-----3------3-----5-----5------5------- 
D|----1-1---1-1---1-----3-3---3-3---3-5-- 
G|--------------------------------------------- 
 
(2nd time) 
 
E|---------------------------------------------- 
A|--3-----3------3-----5-----5------5------- 
D|----1-1---1-1---1-----3-3---3-3---3-5-- 
G|--------------------------------------------- 
 
E|----------------------------- 
A|--4-5----4-5---4-5-------- 
D|-------3------5------3-4-5- 
G|----------------------------- 
 
Riff I and repeat on and on the 1st time. 
 
Riff II 
 
Bridge:   
 
G  /  D  /  C  / G 
 
Repeat riff I on and on. 
 
Bridge II: 
 
G  /  C  / G  /  C 
  
Riff II ends like this: 
 
E|--------------------------------------------------------3--- 
A|-3-----3------3-----5------5------4-5---4-5---4-5---5-- 
D|---1-1---1-1---1-----3-3----3-3------3-----5----------5 
G|-------------------------------------------------------------3-