I never really cared for coffee, but I can appreciate how some people really and truly need their java. Dave Grohl took it a leetle too far and this is what we got, a drummer completely hepped up on caffeine.
From what I gathered he was beyond burning the candle at both ends. He was rehearsing with the Foo Fighters during the day, working with his side project Them Crooked Vultures at night, and had an infant at home.
He has since learned to scale it back.