I walked on a doormat today that reads Immer schön SauBär and has a picture of a bear with a pig’s nose. Now, doormats are crucial for keeping your home sauber and sauber sounds very much like a combination of the two nouns die Sau and der Bär – the “sow” and the “bear.” I am guessing that part of what makes it funny if you are a native speaker of German is that there is the fixed expression immer schön sauber bleiben. Unfortunately, in my search for the meaning of this phrase I was only able to find two shortened forms, Bleib sauber! – “keep your nose clean” or “take care” or “keep yourself clean” – and sauber bleiben – “to go straight” or “to keep out of trouble.” However, I did find lots of articles, videos, etc. entitled Immer schön sauber bleiben.
For example, here is a video from the US about littering: http://www.clipfish.de/video/3778814/immer-schoen-sauber-bleiben/
And here is a list of how to separate your rubbish from the city of Herne: http://www.herne.de/kommunen/herne/entsorgung/www.nsf/0/18b9d3381735bbb2c125753900437624/$FILE/Flyer_Abfalltrennung.pdf
And an article on the grooming habits of the ancient Romans: http://www.geo.de/GEOlino/mensch/roemerbad-immer-schoen-sauber-bleiben-67841.html
And finally, an apron with a rock ‘n roll theme for keeping you clean: http://www.amazon.de/Immer-sch%C3%B6n-sauber-bleiben-Sch%C3%BCrze/dp/B00AE94MOC
All of this variety made it hard to make a clean and sober assessment of what the full phrase immer schön sauber bleiben means.