The greatest concert and spiritual acid journey ever. In which, two women gave birth, millions conceived, and one death was recorded. Used in an excuse or phrase for doing something unexplainable by referencing the event called Woodstock and can be used in the combination with "because" and "doesn't matter"
Bro: You getten' erect in the locker room
Other guy: Doesn't matter man its Woodstock.
Little Brother: why are you on the roof
Big Bro: Because it woodstock! (jumps to shallow end in pool while on acid)