there is no real reason not to place a framed self-portrait in your toilet. it should be something realistic – not too abstract. when guests use your toilet they will see the portrait. they will think about you and think about the way you see yourself. then, they will wonder why you have placed this self-portrait in your toilet. they will imagine you using the toilet, looking at yourself, a version of yourself you have indeed created. your guests will wonder at your inscrutable motives and but they will emerge from the toilet and strike up conversation about something unrelated.
if you like you could also create a word document titled ‘rooms i might mount my self-portrait in.docx’. the document could list most of the rooms in your house, or, it could list just a few (the contents of the document might only be * toilet * laundry). and you could print it off this document. you could leave it somewhere where it is sure to be observed, say pinned to the fridge by a magnet.
the point is you really need some good reasons not to do these things. otherwise you may as well just be sitting still.