I don't even want to think about this. Bending over to pick up the soap might lead to untoward events.

Easy, conserves water and is Fun too.

YEAH!!!Or girlfriend, comely neighbor, the girl next door, the librarian...

When I shower with a partner it has bugger all to do with preserving the environment.....

I enjoy a nice 2 person shower, but I don't think it saves too much water. If the purpose is bathing, unless you have a lot of space in your shower and a showerhead with an amazing range, then you probably can't lather and rinse at the same time. I've never researched this, but I imagine two people showering at one time isn't much more efficient than two individual showers. If you are showering for non bathing reasons...Have Fun and don't worry about wasting water!

Does showering with someone else's wife count?

LOL, seems like a good idea, but 1) you're probably doing it for non-environmental reasons, and 2) you'll spend more time in the shower, anyway, thus negating any water savings that you're expecting.