The first time a PLB was used in the US, it was by a guy from Ohio who was canoeing in upstate NY and got stranded in the snow. He set it off and was rescued. A couple of weeks later, he went back to get his gear and set it off again so he could get another helo ride. The second time he got arrested and fined for misusing it.
http://www.equipped.com/plb_first_use.htm

Another article on the misuse of the PLB, headlined "Yuppie 911"
http://www.msnbc.msn.com/id/33470581/ns/us_news-life/

This story highlights the fact that people assume that a ride is just a call away, so why bother to actually prepare properly for where they are going.