A Science Geek and a Math Whiz Walk into a Bathroom...

And it goes something like this:

Me (seeing that the water never drained from the tub after Arizona's shower, cognizant that its Friday, we have weekend company coming, kayaking is on the to-do list, and folks are probably going to want to shower after ... and wondering idly whether he thinks the stopped-drain fairy is going to come fix it, or if it's going to heal itself if he ignores it long enough): *Pours slug of Draino into five inches of water.* *Hopes this works, because otherwise we're going to be dealing with a stopped-up drain covered by twenty or so gallons of Draino-laced water.*

A couple of hours later ...

Me (seeing that the water level hasn't moved): *Vigorously applies toilet plunger to shower drain.* *Gets nowhere.* *Adds more Draino.*

Later that afternoon ... 

Me (seeing that the drain has not, in fact, healed itself): Where is the snake we bought a couple of months ago to fix this for real?
Arizona: *Points to spare room.*
Me (digs out snake, reads instructions, decides to wing it): Step one. Find rubber gloves. Step two. Bail out tub, preferably without acquiring too many chemical burns.
(By the time this is completed, this has required a frying pan, a lobster pot, a small pump that I promptly broke, and the bilge pump out of the kayak, over which Arizona hovers.)
Me: Next up, unscrew strainer thingie on drain, put snake down hole, twirl either by hand or with power drill. Ohhh-kay. 
(Unscrews strainer thingie. Discovers that there's a crossbar below that won't let the snake through.)
Me: *bad language* (goes online, discovers instructions to unscrew crossbar thingie, along with some vague warnings. Decide I don't want to make this decision unilaterally)
(Goes and gets Arizona. Conference ensues. We agree to unscrew the crossbar thingie, even though there's a seal and putty involved. We can re-putty, right?)
Me (unscrews crossbar thingie, removes unit, gags over crap that comes out with it). Okay. Snake time. 
Arizona (staring at plumbing): That doesn't look good.
(Due to renovations, there are like eight right angles between our shower drain and the actual line.)
Me: *bad language* Well, let's try it anyway.
(We try. We fail.)
Arizona: How about the air compressor? Maybe we can blow out the clog.
Me: Go for it.
(We try. We fail.)

Five minutes later ...

Arizona (from downstairs): Jess? We've got a problem! Get towels!
(This moves to the top of Things I Don't Want To Hear Right Now.)
Me (hustles downstairs, finds that it is raining through the ceiling tiles, onto my elliptical): *really bad language*
(We spread Wet Things on driveway, mop up, remove ceiling tiles, and do what we should have done in the first place, namely call Todd The Plumber. It is now 5 pm Friday.)

6:30 pm Friday. Company has arrived, but so has Todd The Plumber!

TTP (gazes down at tub): You really shouldn't have broken that seal, you know. And if you're going to snake, you want to do it higher up.
Arizona: Can you fix the clog?
TTP (crouches down, studies setup, flips the little lever that closes the drain to fill the tub): There you go. Clog fixed. Though, of course, now we need to replace the other stuff you guys broke.

Yep. However many hundreds of IQ points between me and Arizona, and neither of us had thought to check whether the little lever had gotten flipped. Or we each thought the other had checked. Sigh. Another day in the life ....

On the up-side, we took Todd the Plumber out for pizza with our company (he's a good guy), and had showers for the weekend. All hail the local tradesmen who are willing to dump their Friday night plans to undo their customers' DIY mayhem!