It's pretty much the same bass line the whole song through, it goes like this:
G|--------------------------------|----------------------------------|
D|----5-5-----5-5-----5-5-----5-5-|----2-2-----2-2-----2-2-------2---|
A|--------------------------------|----------------------------------|
E|-3-------3-------3-------3------|-0-------0-------0-------00----0-|
Very easy, and very fun. Great song too. Enjoy!