Definition of "wazoo"

"When you get burned once," Markham continued, "as I did in 'Second Hundred Years' ... where I got my wazoo shot off ..."

1969 September 3, Richard K. Shull, “What 'Mr. Deeds' Is Depends On Speaker”, in Indianapolis News‎, page 19

Even now, in the spring, the river softly cries, 'Menthol, Menthol, you are one wazoo. One day I'm the elf next door and the poof I'm a river.'

1969, Beard & Kennedy, Bored of the Rings, page 87