Oh not more bumper stickers - no, not more bumper stickers. Today's puzzling phenomenon never appears on bumpers but always on back windows, usually those of station wagons (estate cars for English readers, I gather).
I've been noticing it for about a year now, I think, although possibly it's been there longer and I've been slow on the uptake. I don't know whether it's confined to Australia, whether we imported it from somewhere else, or whether it's a worldwide craze, in which case someone is making a great deal of money from it:
Once again, I'm confused by my fellow human beings and by life in general. As a contestant on the Great British Sewing Bee (my current all time favourite television programme) said, after sewing her skirt inside out to her bodice, 'I think I'll go and drown in a bucket of gin."