Didn't know "surf's up" was a song of celebration. Come to think it, channeling my inner Mike Love, I have know idea what the hell that song is about.
"It’s a man at a concert. All around him there’s the audience, playing their roles, dressed up in fancy clothes, looking through opera glasses, but so far away from the drama…Empires, ideas, lives, institutions—everything has to fall, tumbling like dominoes. He begins to awaken to the music; sees the pretentiousness of everything…A choke of grief. At his own sorrow and the emptiness of his life, because he can’t even cry for the suffering in the world, for his own suffering. And then, hope. Surf’s up!…I heard the word—of God; Wonderful thing—the joy of enlightenment, of seeing God. And what is it? A children’s song! And then there’s the song itself; the song of children; the song of the universe rising and falling in wave after wave, the song of God, hiding His love from us, but always letting us find Him again, like a mother singing to her children. Of course that’s a very intellectual explanation. But maybe sometimes you have to do an intellectual thing. If they don’t get the words, they’ll get the music, because that’s where it’s really at, in the music." — Brian Wilson, 1967
So it is pretty celebratory in a way. It's a celebration of the power of music.