buck waving his arms like a bird

Buck Mulligan at once put on a blithe broadly smiling face. He looked at them, his wellshaped mouth open happily, his eyes, from which he had suddenly withdrawn all shrewd sense, blinking with mad gaiety. He moved a doll’s head to and fro, the brims of his Panama hat quivering, and began to chant in a quiet happy foolish voice:

     —I'm the queerest young fellow that ever you heard.
     My mother's a jew, my father's a bird.
     With Joseph the joiner I cannot agree.
     So here's to disciples and Calvary.

He held up a forefinger of warning.

     —If anyone thinks that I amn't divine
     He'll get no free drinks when I'm making the wine
     But have to drink water and wish it were plain
     That i make when the wine becomes water again.

He tugged swiftly at Stephen’s ashplant in farewell and, running forward to a brow of the cliff, fluttered his hands at his sides like fins or wings of one about to rise in the air, and chanted:

     —Goodbye, now, goodbye! Write down all I said
     And tell Tom, Dick and Harry I rose from the dead.
     What's bred in the bone cannot fail me to fly
     And Olivet's breezy... Goodbye, now, goodbye!