The OED has wazoo, n., glossed as "The buttocks; the anus", noting that it is used "Freq. as a (euphemistic) substitute for ass in fig. phrases, as pain in the wazoo, etc.", giving special notice to the expression up (also out) the wazoo, glossed as "in great quantities, in abundance, to excess.
Wiktionary has the gloss "(vulgar, slang) the anus; ass", with derived terms listed as up the wazoo and out the wazoo, both glossed as "(vulgar, idiomatic) up the ass; excessive or excessively; too much".
But as a result of phonetic processes like those discussed here the other day, the pronunciation of the in a phrase like "up the wazoo" often overlaps with what the pronunciation of to would be in a similar context.
Whence the phrasal eggcorns up to wazoo and out to wazoo …
Some web examples:
They have CTAs and images and infographics up to wazoo
If this were a private business, he would be sued up to wazoo.
Dude, those things can be upgraded up to wazoo and compete with a new mac pro
Anyone can pepper their website with keywords and links up to wazoo, but if they're embedded in bad content, you lose points by virtue of their ubiquitous existence.
… Greek salads up to wazoo …
You didn't have to turn your A/v receiver up to wazoo just to get a decent sound level.
it's got creative types up to wazoo who can make it all look rustically attractive and cool,
Each carrier wants the phone customized up to wazoo for them, so we get this kind of fragmentation.
But I still have boxes from our move up to wazoo and honestly, quick and easy dinners is my game.
You'd have to poll up to wazoo to find these caucusgoers
the next thing you know you have a 50 slide masterpiece with titles, photos and transitions out to wazoo
overwhelmed with feeding everyone, keeping everything clean and cleaning after everyone, laundry out to wazoo, my school work, bandage changes etc.
Her parents, who were living in a fabulous condo in Naples, had investments and insurance out to wazoo.
Once we kick out all the illegal immigrants and raise our food prices out to wazoo, will Americans starve to death?
You can still go nuts tweaking it out to wazoo, but it is better functioning right out of the box than a base cygwin install.
Cocktails out to wazoo!
Even though I was spending money out to wazoo on products I was not actually taking the time to implement any of them.
They're really fun but I see a lot of people on here with diamonds out to wazoo and I want to know how this happens lol.
Hope the UFC retains a really good plastics guy, because Mitrione is looking at surgery out to wazoo.
They have solar panels out to wazoo and have conservation programs.
These folks apparently think that Wazoo is some eponymously far-out place, which makes as much sense as anything.
I'll close with a serendipitous discovery.
The OED's earliest citation for wazoo is from 1961. I'm sure that it's older than that, but my attempt to antedate the citation fetched mostly OCR errors, one of which connected me with the middle of The American Magazine for August, 1919, and this bizarre advertisement:
[Larger-format text here.]
Somehow this reminds me of Bruce Sterling's equally bizarre Pirate Utopia. In a world where advertisements like this one could be written and published, Franco Marinetti's Futurist Manifesto was not all that much further towards Wazoo.
Or maybe there were some fugitive Futurists working for R.J. Reynolds' ad agency in 1919?