During my short stay in Berlin, I went to Hell and back during the day, and spent the evening in the toilet.
Not quite as bad as it sounds - 'Hell' was a cafe/wine bar across the road from my hotel, and the Toilet bar 'Klo' is a bit further into town. That sounds like a geeky, deliberately constructed joke on my part, but it just kind of happened. And yes, a toilet-themed pub is probably the worst business idea ever. The Germans don't carry it off with "carry-on" type humour - the bar staff are very serious and miserable, and clientele seem irritated when the toilets around the bar "flush".
But Hell was quite pleasant, seemingly one of the trendiest bars around.
Wilmersdorf
Is this your business?