Shopdropping, not too surprisingly, is the reverse of shoplifting. It started as a US guerrilla-art movement that wanted to utilise public spaces for artists to exhibit. Artists would for example replace can labels with new ones that conveyed a political or consumerist message.The term has since been used to describe any unauthorised placing of materials in stores. Independent bands, for instance, sometimes put copies of their albums in stores to promote them. And some self-published authors do the same with their books, just to get the word out there.
Don’t go getting any ideas now...