Zillyhoo is the name of the war hammer that John Egbert obtains at one point in the popular web-comic Homestuck. It's sheer beauty and awesomeness astonishes the Wayward Vagabond, Courtyard Droll, and Karkat Vantas. The awesomeness of the war hammer compels John to to sing a majestic chorus to an imaginary cathedral window. It also appears in Andrew Hussie's other web comic called Problem Sleuth.
bunny: *largify Warhammer of Zillyhoo*
John: *obtain Warhammer of Zillyhoo*
WV, CD, and Karkat: *be astonished*
John: *sing a chorus to a fake cathedral window*