More info for people new to San Francisco...
Turns out you'll slip right in to the city if you carry something weird and possibly household-related as you walk the streets. I had a rather unnatural sense of comfort while strolling near Dolores Park late at night - simply because I was carrying two cushions.
Many people wander around with many things, and its undeniably a definining feature of the city that many, many street corners are covered in detritus. There seems to be an entire ecosystem devoted to the release and collection of crap. Some crap is lovely crap, some crap is just plain crap.
If I paint myself as a carrier of crap, then all is well.