Basically it's D - G - D - A OR E - A - E - B
The strum pattern is a bit fast so I'd recommended watching the actual song to 
figure it out. I just do up-down-up-down-up really fast xD

D                                  G
Beer beer beer beer beer beer beer beer beer beer beer beer beer beer    {Repeat as
D                                  A                                     many times as
Beer beer beer beer beer beer beer beer beer beer beer beer beer beer     you like}