If not already clear, this comment was absolutely meant as a complement to you. I plan to teach this phrase to my continental coworkers when they visit us in the US next week. They're always seeking ways to expand their English language skills.

And since they continue to challenge me about the acceptability (in US english) over the phrase "Ulrike washes her coffee cup in the toilet every day," I think this is fair. We would accept: washroom, restroom, or bathroom without thinking twice. We might even pass over "in the shitter" and although it would be considered much less polite it would be excusable in a non-native speaker and probably not even noticeable in some of the more salty regions of the US.

"Washed it in the toilet..."

I do love language.