German Idioms related to "The Little Boys Room"

Every language has interesting ways to describe the act of going to the toilet or "popping to the loo" as we say in the UK. In fact, bathroom idioms are part of everyday life not just in English but in German too. 

Here are a few German language expressions that I have found related to the WC. If you know of any more I would be very interested to hear them.  

Cartoon by Hule

"Wo der König allein hingeht" 

Where the king goes alone

"Sie sind ebenso schmutzig wie Toilettenpapier"

You're just as dirty as toilet paper

"Das stille Örtchen"

The quiet place (the toilet)

"Wo der Kaiser zu Fuß hingeht"

Where the Kaiser goes on foot

I imagine a king every time I go to the loo now. It makes the whole "process" a lot more fun :P