It seems that the word "wazoo" was coined in the California Pelican magazine at the University of California, Berkeley in 1961. Thanks, OED!
wazoo, n.
slang (orig. and chiefly U.S.).
Show pronunciation* Show etymology* Hide quotations* Show date charts*
1. The buttocks; the anus.
Freq. as a (euphemistic) substitute for ass in fig. phrases, as pain in the wazoo, etc.
1961 Calif. Pelican (Univ. Calif., Berkeley) May (back cover) Run it up yer ol' wazoo! 1971 Wall St. Jrnl. 20 Apr. 1 Golf itself is quite safe, the greatest risk being the possibility of a long drive plunking some poor fellow in the wazoo. 1975 San Francisco Chron. 14 Feb. 40 Dating is a real pain in the wazoo. 1995 Esquire Oct. 60/2 When we step forward to seek acclaim, to be raised up above the crowd, we can expect spears up the wazoo. 2002 Sunday Herald (Glasgow) 13 Jan. (Review section) 16/5 Every band of half-wits that sails out of the NME's wazoo is immediately hailed as next in line for The Beatles' throne.2. up (also out) the wazoo: in great quantities, in abundance, to excess.
1981 Syracuse (N.Y.) Herald-Jrnl. 5 Jan. D8/3 There comes a time in performing when you just do it. You can have theory up the wazoo. 1983 Amer. Bar. Assoc. Jrnl. (Nexis) June 69 834, I had done well{em}law review, Coif, American Jurisprudence book awards up the wazoo. 1991 T. DEITZ Soulsmith 10, I know for a fact that he's well provided for and insured out the wazoo. 2003 L. BLOCK Small Town 453 There'd be security up the wazoo, cops and Secret Service agents a mile deep.