A glass lens doorknob. You'd really want this to be one-way in most cases. But doors to (say) kitchens which swing in-and-out would benefit.
The funniest sentence on the Internet today, Rogers on his terrible experience on an amusement park ride:
Afterward, the various twelve-year olds regarded me with pity. Pity. Do you know how far you have to fall in an adolescent's eyes before you drop below scorn? They're hard-wired for scorn. The evening ended with my wife actually taking me to the petting zoo for a bit, to collect myself, before we headed home.